Stabilized intervertebral disc barrier

ABSTRACT

Presented are new resilient sheet-like surgical meshes that may be compressed for minimally invasive delivery in the intervertebral discs. According to one or more embodiments, the surgical mesh can be robust, fatigue resistant, stable and capable of withstanding the dynamic environment generic to intervertebral discs.

RELATED APPLICATIONS

This application claims benefit to U.S. Provisional Application No.60/513,437, filed Oct. 22, 2003 and U.S. Provisional Application No.60/613,958, filed Sep. 28, 2004, and is a continuation-in-part of U.S.application Ser. No. 10/194,428, filed Jul. 10, 2002, now U.S. Pat. No.6,936,072, and is a continuation-in-part of U.S. application Ser. No.10/055,504, filed Oct. 25, 2001, now U.S. Pat. No. 7,258,700, which is acontinuation-in-part of U.S. application Ser. No. 09/696,636 filed onOct. 25, 2000, now U.S. Pat. No. 6,508,839, which is acontinuation-in-part of U.S. application Ser. No. 09/642,450 filed onAug. 18, 2000, now U.S. Pat. No. 6,482,235, which is acontinuation-in-part of U.S. application Ser. No. 09/608,797 filed onJun. 30, 2000, now U.S. Pat. No. 6,425,919, and claims benefit to U.S.Provisional Application No. 60/311,586 filed Aug. 10, 2001, U.S.Provisional Application No. 60/149,490 filed Aug. 18, 1999, U.S.Provisional Application No. 60/161,085 filed Oct. 25, 1999 and U.S.Provisional Application No. 60/172,996 filed Dec. 21, 1999, the entireteachings of these applications being incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the surgical treatment ofintervertebral discs in the lumbar, cervical, or thoracic spine thathave suffered from tears in the anulus fibrosis, herniation of thenucleus pulposus and/or significant disc height loss.

2. Description of the Related Art

The disc performs the important role of absorbing mechanical loads whileallowing for constrained flexibility of the spine. The disc is composedof a soft, central nucleus pulposus (NP) surrounded by a tough, wovenanulus fibrosis (AF). Herniation is a result of a weakening in the AF.Symptomatic herniations occur when weakness in the AF allows the NP tobulge or leak posteriorly toward the spinal cord and major nerve roots.The most common resulting symptoms are pain radiating along a compressednerve and low back pain, both of which can be crippling for the patient.The significance of this problem is increased by the low average age ofdiagnosis, with over 80% of patients in the U.S. being under 59.

Since its original description by Mixter & Barr in 1934, discectomy hasbeen the most common surgical procedure for treating intervertebral discherniation. This procedure involves removal of disc materials impingingon the nerve roots or spinal cord external to the disc, generallyposteriorly. Depending on the surgeon's preference, varying amounts ofNP are then removed from within the disc space either through theherniation site or through an incision in the AF. This removal of extraNP is commonly done to minimize the risk of recurrent herniation.

Nevertheless, the most significant drawbacks of discectomy arerecurrence of herniation, recurrence of radicular symptoms, andincreasing low back pain. Re-herniation can occur in up to 21% of cases.The site for re-herniation is most commonly the same level and side asthe previous herniation and can occur through the same weakened site inthe AF. Persistence or recurrence of radicular symptoms happens in manypatients and when not related to re-herniation, tends to be linked tostenosis of the neural foramina caused by a loss in height of theoperated disc. Debilitating low back pain occurs in roughly 14% ofpatients. All of these failings are most directly related to the loss ofNP material and AF competence that results from herniation and surgery.

Various implants, surgical meshes, patches, barriers, tissue scaffoldsand the like may be used to treat intervertebral discs and are known inthe art. Surgical repair meshes are used throughout the body to treatand repair damaged tissue structures such as intralinguinal hernias,herniated discs and to close iatrogenic holes and incisions as may occurelsewhere. Certain physiological environments present challenges toprecise and minimally invasive delivery.

An intervertebral disc provides a dynamic environment that produces highloads and pressures. Typically implants designed for this environmentmust be capable of enduring such conditions for long periods of time.Also, the difficulty and danger of the implantation procedure itself,due to the proximity of the spinal cord, limits the size and ease ofplacement of the implant. One or more further embodiments of theinvention addresses the need for a durable fatigue resistant repair meshcapable of withstanding the dynamic environment generic tointervertebral discs.

SUMMARY OF THE INVENTION

Several embodiments of the present invention relate generally to anulusaugmentation devices, including, but not limited to, surgical meshes,barriers, and patches for treatment or augmentation of tissues withinpathologic spinal discs. One or more embodiments comprise resilientsurgical meshes that may be compressed for minimally invasive deliveryand which are robust, stable, and resist fatigue and stress. Thesemeshes are particularly well suited for intervertebral disc applicationsbecause they are durable enough to withstand intense cyclical loadingand resist expulsion through a defect while not degrading over time.

Several embodiments of the present invention seek to exploit theindividual characteristics of various anulus and nuclear augmentationdevices to optimize the performance of both within the intervertebraldisc. Accordingly, one or more of the embodiments of the presentinvention provide minimally invasive and removable devices for closing adefect in an anulus and augmenting the nucleus. These devices may bepermanent, semi-permanent, or removable. One function of anulusaugmentation devices is to prevent or minimize the extrusion ofmaterials from within the space normally occupied by the nucleuspulposus and inner anulus fibrosus. One function of nuclear augmentationdevices is to at least temporarily add material to restore diminisheddisc height and pressure. Nuclear augmentation devices can also inducethe growth or formation of material within the nuclear space.Accordingly, the inventive combination of these devices can create asynergistic effect wherein the anulus and nuclear augmentation devicesserve to restore biomechanical function in a more natural biomimeticway. Furthermore, in one embodiment, both devices may be delivered moreeasily and less invasively. Also, in some embodiments, the pressurizedenvironment made possible through the addition of nuclear augmentationmaterial and closing of the anulus serves both to restrain the nuclearaugmentation and anchor the anulus augmentation in place.

As used herein, the phrase “anulus augmentation device” shall be givenits ordinary meaning and shall also include devices that at leastpartially cover, close or seal a defect in an intervertebral disc,including, for example, barriers, meshes, patches, membranes, sealingmeans or closure devices. Thus, in one sense, the anulus augmentationdevice augments the anulus by sealing a defect in the anulus. In someembodiments, one or more barriers, meshes, patches, membranes, sealingmeans or closure devices comprise a support member or frame. Thus, inone embodiment, a barrier that comprises a membrane and a frame isprovided. As used herein, the terms augmenting or reinforcing (andvariations thereto) shall be given their ordinary meaning and shall alsomean supporting, covering, closing, patching, or sealing.

In one embodiment, one or more anulus augmentation devices are providedwith one or more nuclear augmentation devices. In some embodiments, theanulus barrier is integral with the nucleus augmentation. In otherembodiments, at least a portion of the barrier is separate from orindependent of the nuclear augmentation.

One or more of the embodiments of the present invention additionallyprovide an anulus augmentation device that is adapted for use withflowable nuclear augmentation material such that the flowable materialcannot escape from the anulus after the anulus augmentation device hasbeen implanted.

In one embodiment of the present invention, a disc augmentation systemconfigured to repair or rehabilitate an intervertebral disc is provided.The system comprises at least one anulus augmentation device, and atleast one nuclear augmentation material. The anulus augmentation deviceprevents or minimizes the extrusion of materials from within the spacenormally occupied by the nucleus pulposus and inner anulus fibrosus. Inone application of the invention, the anulus augmentation device isconfigured for minimally invasive implantation and deployment. Theanulus augmentation device may either be a permanent implant, or it mayremovable.

The nuclear augmentation material may restore diminished disc heightand/or pressure. It may include factors for inducing the growth orformation of material within the nuclear space. It may either bepermanent, removable, or absorbable.

The nuclear augmentation material may be in the form of liquids, gels,solids, or gases. In one embodiment, the nuclear augmentation materialcomprises materials selected from the group consisting of one or more ofthe following: steroids, antibiotics, tissue necrosis factors, tissuenecrosis factor antagonists, analgesics, growth factors, genes, genevectors, hyaluronic acid, noncross-linked collagen, collagen, fibren,liquid fat, oils, synthetic polymers, polyethylene glycol, liquidsilicones, synthetic oils, saline and hydrogel. The hydrogel may beselected from the group consisting of one or more of the following:acrylonitriles, acrylic acids, polyacrylimides, acrylimides,acrylimidines, polyacrylnitriles, and polyvinyl alcohols.

Solid form nuclear augmentation materials may be in the form ofgeometric shapes such as cubes, spheroids, disc-like components,ellipsoid, rhombohedral, cylindrical, or amorphous. The solid materialmay be in powder form, and may be selected from the group consisting ofone or more of the following: titanium, stainless steel, nitinol,cobalt, chrome, resorbable materials, polyurethane, polyesther, PEEK,PET, FEP, PTFE, ePTFE, PMMA, nylon, carbon fiber, Delrin, polyvinylalcohol gels, polyglycolic acid, polyethylene glycol, silicone gel,silicone rubber, vulcanized rubber, gas-filled vesicles, bone, hydroxyapetite, collagen such as cross-linked collagen, muscle tissue, fat,cellulose, keratin, cartilage, protein polymers, transplanted nucleuspulposus, bioengineered nucleus pulposus, transplanted anulus fibrosis,and bioengineered anulus fibrosis. Structures may also be utilized, suchas inflatable balloons or other inflatable containers, and spring-biasedstructures.

The nuclear augmentation material may additionally comprise abiologically active compound. The compound may be selected from thegroup consisting of one or more of the following: drug carriers, geneticvectors, genes, therapeutic agents, growth renewal agents, growthinhibitory agents, analgesics, anti-infectious agents, andanti-inflammatory drugs.

In one embodiment, the anulus augmentation device comprises materialsselected from the group consisting of one or more of the following:steroids, antibiotics, tissue necrosis factors, tissue necrosis factorantagonists, analgesics, growth factors, genes, gene vectors, hyaluronicacid, noncross-linked collagen, collagen, fibren, liquid fat, oils,synthetic polymers, polyethylene glycol, liquid silicones, syntheticoils, saline, hydrogel (e.g., acrylonitriles, acrylic acids,polyacrylimides, acrylimides, acrylimidines, polyacrylnitriles, andpolyvinyl alcohols), and other suitable materials.

In some embodiments, the anulus augmentation device is constructed fromone or more of the following materials: titanium, stainless steel,nitinol, cobalt, chrome, resorbable materials, polyurethane, polyesther,PEEK, PET, FEP, PTFE, ePTFE, PMMA, nylon, carbon fiber, Delrin,polyvinyl alcohol gels, polyglycolic acid, polyethylene glycol, siliconegel, silicone rubber, vulcanized rubber, gas-filled vesicles, bone,hydroxy apetite, collagen such as cross-linked collagen, muscle tissue,fat, cellulose, keratin, cartilage, and protein polymers. Transplantedanulus fibrosis and bioengineered anulus fibrosis may also be used toform the barrier, sealing device, closing device or membrane. Inflatableballoons or other inflatable containers, and spring-biased structuresmay also be used.

The anulus augmentation device may comprise a biologically activecompound. The compound may be selected from the group consisting of oneor more of the following: drug carriers, genetic vectors, genes,therapeutic agents, growth renewal agents, growth inhibitory agents,analgesics, anti-infectious agents, and anti-inflammatory drugs. In someembodiments, the biologically active compound is coupled to the barrier,sealing device, closing device or membrane. In some embodiments, thebiologically active compound coats the barrier, sealing device, closingdevice or membrane.

In one embodiment, an anulus augmentation device for reinforcing anintervertebral disc is provided. In one embodiment, the anulusaugmentation device comprises a mesh frame, wherein the mesh framecomprises a plurality of flexible curvilinear members. In oneembodiment, the curvalinear elements are interconnected. Theinterconnected curvilinear members are adapted to provide flexibilityand resilience to the mesh frame. In some embodiments, the curvilinearmembers form a horizontal member or central strut. In one embodiment,the curvilinear members are arranged in a parallel configuration.

In one embodiment, the curvilinear members comprise a metal alloy suchas steel, nickel titanium, cobalt chrome, or combinations thereof.

In some embodiments, the curvilinear members are constructed of nylon,polyvinyl alcohol, polyethylene, polyurethane, polypropylene,polycaprolactone, polyacrylate, ethylene-vinyl acetate, polystyrene,polyvinyl oxide, polyvinyl fluoride, polyvinyl imidazoles,chlorosulphonated polyolefin, polyethylene oxide,polytetrafluoroethylene, acetal, poly(p-phenyleneterephtalamide)(Kevlar™), poly carbonate, carbon, graphite, or a combination thereof.

In one embodiment, a membrane encapsulates, covers or coats at least aportion of the mesh frame. In some embodiments, the membrane is coupledto the frame.

The membrane of some embodiments is constructed of polymers, elastomers,gels, elastin, albumin, collagen, fibrin, keratin, or a combinationthereof. In several embodiments, the membrane comprises antibodies,antiseptics, genetic vectors, bone morphogenic proteins, steroids,cortisones, growth factors, or a combination thereof. The membrane maybe a coating material.

In one embodiment, the mesh frame is concave along at least a portion ofat least one axis of said mesh frame. In one embodiment, the mesh framehas a length in the range of about 0.5 cm to about 5 cm. One of skill inthe art will understand that other lengths can also be used. In someembodiments, the mesh frame is sized to cover at least a portion of aninterior surface of an anulus lamella. In other embodiments, the meshframe is adapted to extend circumferentially along the entire surface ofan anulus lamella.

In one embodiment, an anulus augmentation device comprising at least oneprojection that radiates from a mesh frame is provided. In oneembodiment, the mesh frame has a vertical cross-section that is flat,concave, convex, or curvilinear. The horizontal cross-section can beconcave, convex, flat, or kidney bean shaped. Other shapes can also beused.

In one embodiment of the present invention, an anulus augmentationdevice for reinforcing an intervertebral disc comprises a mesh framehaving a horizontal axis and a vertical axis. In one embodiment, themesh fame is concave along at least a portion the horizontal axis or thevertical axis. In one embodiment, one or more projections radiate fromthe horizontal axis or the vertical axis of the mesh frame. Theprojections are adapted to stabilize the anulus augmentation device. Inone embodiment, a stabilizing projection has at least one dimension thatis larger than the mesh frame. In other embodiments, the projection issmaller than the mesh frame.

In yet another embodiment of the present invention, an intervertebraldisc implant comprising a posterior support member having a firstterminus and a second terminus is provided. In one embodiment, ananterior projection extends outwardly from the posterior support member.The anterior projection is attached to at least the first terminus orthe second terminus of the posterior support member.

In another embodiments, an intervertebral disc implant comprising aposterior support member having a first terminus and a second terminusand an anterior projection having a first end and a second end isprovided. The anterior projection extends outwardly from the posteriorsupport member. In one embodiment, the first end of the anteriorprojection is coupled to the first terminus of the posterior supportmember; and the second end of the anterior projection is coupled to thesecond terminus of the posterior support member, thereby substantiallyforming a bow-shaped implant. The posterior support member and theanterior projection can be constructed of any suitable material,including but not limited to the materials described above for the meshframe and the membrane.

In a further embodiment of the present invention, a fatigue-resistantsurgical mesh comprising rails is provided. In one embodiment, the meshcomprises a top rail, a bottom rail coupled to the top rail, wherein thetop rail and said bottom rail are coupled to each other at a first endand second end. In one embodiment, the top rail and the bottom railextend to form a gap that is defined between the rails along at least aportion of the distance between the ends.

In one embodiment of the present invention, a spinal implant fortreatment of an intervertebral disc is provided. In one embodiment, abarrier or patch with a volume corresponding to the amount of materialremoved during a discectomy procedure is implanted. In one embodiment,the implant has a volume in a range of about 0.2 to about 2.0 cc.

In one embodiment of the invention, an intervertebral disc implantcomprising a barrier forming a contiguous band is provided. In oneembodiment, the band has variable heights or widths. In one embodiment,the band has different degrees of flexibility along at least one axis.

In another embodiment of the present invention, a method of repairing orrehabilitating an intervertebral disc is provided. The method comprisesinserting at least one anulus augmentation device into the disc, andinserting at least one nuclear augmentation material, to be held withinthe disc by the anulus augmentation device. The nuclear augmentationmaterial may conform to a first, healthy region of the anulus, while theanulus augmentation device conforms to a second, weaker region of theanulus.

In a further embodiment, a method of repairing defective regions withina spinal disc is provided. In one embodiment, the method comprisesproviding a surgical mesh, implanting the surgical mesh along an anulussurface, and positioning the surgical mesh at least such that about 2 mmof the device spans beyond at least one edge of the defective region ofthe disc.

Further features and advantages of embodiments of the present inventionwill become apparent to those of skill in the art in view of thedetailed description of preferred embodiments which follows, when takentogether with the attached drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1A shows a transverse section of a portion of a functional spineunit, in which part of a vertebra and intervertebral disc are depicted.

FIG. 1B shows a sagittal cross section of a portion of a functionalspine unit shown in FIG. 1A, in which two lumbar vertebrae and theintervertebral disc are visible.

FIG. 1C shows partial disruption of the inner layers of an anulusfibrosis.

FIG. 2A shows a transverse section of one aspect of the presentinvention prior to supporting a herniated segment, as shown in oneembodiment.

FIG. 2B shows a transverse section of the construct in FIG. 2Asupporting the herniated segment.

FIG. 3A shows a transverse section of another embodiment of thedisclosed invention after placement of the device.

FIG. 3B shows a transverse section of the construct in FIG. 3A aftertension is applied to support the herniated segment.

FIG. 4A shows a transverse view of an alternate embodiment of theinvention.

FIG. 4B shows a sagittal view of the alternate embodiment shown in FIG.4A.

FIG. 5A shows a transverse view of another aspect of the presentinvention, as shown in one embodiment.

FIG. 5B shows the delivery tube of FIG. 5A being used to displace theherniated segment to within its pre-herniated borders.

FIG. 5C shows a one-piece embodiment of the invention in an anchored andsupporting position.

FIG. 6 shows one embodiment of the invention supporting a weakenedposterior anulus fibrosis.

FIG. 7A shows a transverse section of another aspect of the disclosedinvention demonstrating two stages involved in augmentation of the softtissues of the disc.

FIG. 7B shows a sagittal view of the invention shown in FIG. 7A.

FIG. 8 shows a transverse section of one aspect of the disclosedinvention involving augmentation of the soft tissues of the disc andsupport/closure of the anulus fibrosis.

FIG. 9A shows a transverse section of one aspect of the inventioninvolving augmentation of the soft tissues of the disc with the flexibleaugmentation material anchored to the anterior lateral anulus fibrosis.

FIG. 9B shows a transverse section of one aspect of the disclosedinvention involving augmentation of the soft tissues of the disc withthe flexible augmentation material anchored to the anulus fibrosis by aone-piece anchor.

FIG. 10A shows a transverse section of one aspect of the disclosedinvention involving augmentation of the soft tissues of the disc.

FIG. 10B shows the construct of FIG. 10A after the augmentation materialhas been inserted into the disc.

FIG. 11 illustrates a transverse section of a barrier mounted within ananulus.

FIG. 12 shows a sagittal view of the barrier of FIG. 11.

FIG. 13 shows a transverse section of a barrier anchored within a disc.

FIG. 14 illustrates a sagittal view of the barrier shown in FIG. 13.

FIG. 15 illustrates the use of a second anchoring device for a barriermounted within a disc.

FIG. 16A is an transverse view of the intervertebral disc.

FIG. 16B is a sagittal section along the midline of the intervertebraldisc.

FIG. 17 is an axial view of the intervertebral disc with the right halfof a sealing means of a barrier means being placed against the interioraspect of a defect in anulus fibrosis by a dissection/delivery tool.

FIG. 18 illustrates a full sealing means placed on the interior aspectof a defect in anulus fibrosis.

FIG. 19 depicts the sealing means of FIG. 18 being secured to tissuessurrounding the defect.

FIG. 20 depicts the sealing means of FIG. 19 after fixation means havebeen passed into surrounding tissues.

FIG. 21A depicts an axial view of the sealing means of FIG. 20 havingenlarging means inserted into the interior cavity.

FIG. 21B depicts the construct of FIG. 21 in a sagittal section.

FIG. 22A shows an alternative fixation scheme for the sealing means andenlarging means.

FIG. 22B shows the construct of FIG. 22A in a sagittal section with ananchor securing a fixation region of the enlarging means to a superiorvertebral body in a location proximate to the defect.

FIG. 23A depicts an embodiment of the barrier means of the presentinvention being secured to an anulus using fixation means, as shown inone embodiment.

FIG. 23B depicts an embodiment of the barrier means of FIG. 23A securedto an anulus by two fixation darts wherein the fixation tool has beenremoved.

FIGS. 24A and 24B depict a barrier means positioned between layers ofthe anulus fibrosis on either side of a defect.

FIG. 25 depicts an axial cross section of a large version of a barriermeans.

FIG. 26 depicts an axial cross section of a barrier means in positionacross a defect following insertion of two augmentation devices.

FIG. 27 depicts the barrier means as part of an elongated augmentationdevice.

FIG. 28A depicts an axial section of an alternate configuration of theaugmentation device of FIG. 27.

FIG. 28B depicts a sagittal section of an alternate configuration of theaugmentation device of FIG. 27.

FIGS. 29A-D depict deployment of a barrier from an entry site remotefrom the defect in the anulus fibrosis.

FIGS. 30A, 30B, 31A, 31B, 32A, 32B, 33A, and 33B depict axial andsectional views, respectively, of various embodiments of the barrier.

FIG. 34 shows a non-axisymmetric expansion means or frame.

FIGS. 34B and 34C illustrate perspective views of a frame mounted withinan intervertebral disc.

FIGS. 35 and 36 illustrate alternate embodiments of the expansion meansshown in FIG. 34.

FIGS. 37A-C illustrate a front, side, and perspective view,respectively, of an alternate embodiment of the expansion means shown inFIG. 34.

FIG. 38 shows an alternate expansion means to that shown in FIG. 37A.

FIGS. 39A-D illustrate a tubular expansion means having a circularcross-section.

FIGS. 40A-I illustrate tubular expansion means. FIGS. 40A-D illustrate atubular expansion means having an oval shaped cross-section. FIGS. 40E,40F and 40I illustrate a front, back and top view, respectively of thetubular expansion means of FIG. 40A having a sealing means covering anexterior surface of an anulus face. FIGS. 40G and 40H show the tubularexpansion means of FIG. 40A having a sealing means covering an interiorsurface of an anulus face.

FIGS. 41A-D illustrate a tubular expansion means having an egg-shapedcross-section.

FIG. 42A-D depicts cross sections of a preferred embodiment of sealingand enlarging means.

FIGS. 43A and 43B depict an alternative configuration of enlargingmeans.

FIGS. 44A and 44B depict an alternative shape of the barrier means.

FIG. 45 is a section of a device used to affix sealing means to tissuessurrounding a defect.

FIG. 46 depicts the use of a thermal device to heat and adhere sealingmeans to tissues surrounding a defect.

FIG. 47 depicts an expandable thermal element that can be used to adheresealing means to tissues surrounding a defect.

FIG. 48 depicts an alternative embodiment to the thermal device of FIG.46.

FIGS. 49A-G illustrate a method of implanting an intradiscal implant.

FIGS. 50A-F show an alternate method of implanting an intradiscalimplant.

FIGS. 51A-C show another alternate method of implanting an intradiscalimplant.

FIGS. 52A and 52B illustrate an implant guide used with the intradiscalimplant system.

FIG. 53A illustrates a barrier having stiffening plate elements.

FIG. 53B illustrates a sectional view of the barrier of FIG. 53A.

FIG. 54A shows a stiffening plate.

FIG. 54B shows a sectional view of the stiffening plate of FIG. 54A.

FIG. 55A illustrates a barrier having stiffening rod elements.

FIG. 55B illustrates a sectional view of the barrier of FIG. 55A.

FIG. 56A illustrates a stiffening rod.

FIG. 56B illustrates a sectional view of the stiffening rod of FIG. 56A.

FIG. 57 shows an alternate configuration for the location of thefixation devices of the barrier of FIG. 44A.

FIGS. 58A and 58B illustrate a dissection device for an intervertebraldisc.

FIGS. 59A and 59B illustrate an alternate dissection device for anintervertebral disc.

FIGS. 60A-C illustrate a dissector component.

FIGS. 61A-D illustrate a method of inserting a disc implant within anintervertebral disc.

FIG. 62 depicts a cross-sectional transverse view of a barrier deviceimplanted within a disc along the inner surface of a lamella. Implantedconformable nuclear augmentation is also shown in contact with thebarrier.

FIG. 63 shows a cross-sectional transverse view of a barrier deviceimplanted within a disc along an inner surface of a lamella. Implantednuclear augmentation comprised of a hydrophilic flexible solid is alsoshown.

FIG. 64 shows a cross-sectional transverse view of a barrier deviceimplanted within a disc along an inner surface of a lamella. Severaltypes of implanted nuclear augmentation including a solid geometricshape, a composite solid, and a free flowing liquid are also shown.

FIG. 65 illustrates a sagittal cross-sectional view of a barrier deviceconnected to an inflatable nuclear augmentation device.

FIG. 66 depicts a sagittal cross-sectional view of a functional spineunit containing a barrier device unit connected to a wedge shapednuclear augmentation device.

FIG. 67 shows an anulus augmentation device (such as a mesh) mesh havinga series of curvilinear elements.

FIGS. 68A-G show profiles and cross-sectional views of an anulusaugmentation device (such as a mesh), e.g., “U” shaped, “C” shaped,curvilinear shaped, and “D” shaped to extend along and cover the entireinner anulus surface, or portions.

FIG. 69 shows one embodiment of a mesh with curvilinear elementsimplanted in an intervertebral disc.

FIG. 70 shows a wire-type anulus augmentation device.

FIGS. 71A-E show a frame (e.g., mesh) that has been encapsulated by amembrane or cover to produce an encapsulated mesh.

FIGS. 72A-B show a mesh having a double-wishbone frame.

FIGS. 73A-C shows embodiments of the end or natural hinge portion of theframe, including a looped terminus.

FIGS. 74A-C show some embodiments of the central band or strut.

FIGS. 75A-L show an implant an annulus augmentation device such as amesh having one or more projections extending into the disc or into adefect.

FIG. 76 shows an implant comprising a bow-like anterior projection thatextends outwardly from a posterior support member.

FIGS. 77A-H show various cross-sectional side views along a horizontalaxis of an implant comprising a bow, band or projection.

FIGS. 78A-J show various cross-sectional top views of implants along avertical axis.

FIGS. 79A-F show a frontal view of a portion of several embodiments ofan implant projection.

FIGS. 80A-D show various cross-sections of an implant projection.

FIGS. 81A-D show looped or bent bow-type projections.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Several embodiments of the present invention provide for an in vivoaugmented functional spine unit. A functional spine unit includes thebony structures of two adjacent vertebrae (or vertebral bodies), thesoft tissue (anulus fibrosis (AF), and optionally nucleus pulposus (NP))of the intervertebral disc, and the ligaments, musculature andconnective tissue connected to the vertebrae. The intervertebral disc issubstantially situated in the intervertebral space formed between theadjacent vertebrae. Augmentation of the functional spine unit caninclude repair of a herniated disc segment, support of a weakened, tornor damaged anulus fibrosis, or the addition of material to orreplacement of all or part of the nucleus pulposus. Augmentation of thefunctional spine unit is provided by herniation constraining devices anddisc augmentation devices situated in the intervertebral disc space.

FIGS. 1A and 1B show the general anatomy of a functional spine unit 45.In this description and the following claims, the terms ‘anterior’ and‘posterior’, ‘superior’ and ‘inferior’ are defined by their standardusage in anatomy, i.e., anterior is a direction toward the front(ventral) side of the body or organ, posterior is a direction toward theback (dorsal) side of the body or organ; superior is upward (toward thehead) and inferior is lower (toward the feet).

FIG. 1A is an axial view along the transverse axis M of a vertebral bodywith the intervertebral disc 15 superior to the vertebral body. Axis Mshows the anterior (A) and posterior (P) orientation of the functionalspine unit within the anatomy. The intervertebral disc 15 contains theanulus fibrosis (AF) 10 which surrounds a central nucleus pulposus (NP)20. A Herniated segment 30 is depicted by a dashed-line. The herniatedsegment 30 protrudes beyond the pre-herniated posterior border 40 of thedisc. Also shown in this figure are the left 70 and right 70′ transversespinous processes and the posterior spinous process 80.

FIG. 1B is a sagittal section along sagittal axis N through the midlineof two adjacent vertebral bodies 50 (superior) and 50′ (inferior).Intervertebral disc space 55 is formed between the two vertebral bodiesand contains intervertebral disc 15, which supports and cushions thevertebral bodies and permits movement of the two vertebral bodies withrespect to each other and other adjacent functional spine units.

Intervertebral disc 15 is comprised of the outer AF 10 which normallysurrounds and constrains the NP 20 to be wholly within the borders ofthe intervertebral disc space. In FIGS. 1A and 1B, herniated segment 30,represented by the dashed-line, has migrated posterior to thepre-herniated border 40 of the posterior AF of the disc. Axis M extendsbetween the anterior (A) and posterior (P) of the functional spine unit.The vertebral bodies also include facet joints 60 and the superior 90and inferior 90′ pedicle that form the neural foramen 100. Disc heightloss occurs when the superior vertebral body 50 moves inferiorlyrelative to the inferior vertebral body 50′.

Partial disruption 121 of the inner layers of the anulus 10 without atrue perforation has also been linked to chronic low back pain. Such adisruption 4 is illustrated in FIG. 1C. It is thought that weakness ofthese inner layers forces the sensitive outer anulus lamellae to endurehigher stresses. This increased stress stimulates the small nerve fiberspenetrating the outer anulus, which results in both localized andreferred pain.

In one embodiment of the present invention, the disc herniationconstraining devices 13 provide support for returning all or part of theherniated segment 30 to a position substantially within itspre-herniated borders 40. The disc herniation constraining deviceincludes an anchor which is positioned at a site within the functionalspine unit, such as the superior or inferior vertebral body, or theanterior medial, or anterior lateral anulus fibrosis. The anchor is usedas a point against which all or part of the herniated segment istensioned so as to return the herniated segment to its pre-herniatedborders, and thereby relieve pressure on otherwise compressed neuraltissue and structures. A support member is positioned in or posterior tothe herniated segment, and is connected to the anchor by a connectingmember. Sufficient tension is applied to the connecting member so thatthe support member returns the herniated segment to a pre-herniatedposition. In various embodiments, augmentation material is securedwithin the intervertebral disc space, which assists the NP in cushioningand supporting the inferior and superior vertebral bodies. An anchorsecured in a portion of the functional spine unit and attached to theconnection member and augmentation material limits movement of theaugmentation material within the intervertebral disc space. A supportingmember, located opposite the anchor, may optionally provide a secondpoint of attachment for the connection member and further hinder themovement of the augmentation material within the intervertebral discspace.

FIGS. 2A and 2B depict one embodiment of device 13. FIG. 2A shows theelements of the constraining device in position to correct the herniatedsegment. Anchor 1 is securely established in a location within thefunctional spine unit, such as the anterior AF shown in the figure.Support member 2 is positioned in or posterior to herniated segment 30.Leading from and connected to anchor 1 is connection member 3, whichserves to connect anchor 1 to support member 2. Depending on thelocation chosen for support member 2, the connection member may traversethrough all or part of the herniated segment.

FIG. 2B shows the positions of the various elements of the herniationconstraining device 13 when the device 13 is supporting the herniatedsegment. Tightening connection member 2 allows it to transmit tensileforces along its length, which causes herniated segment 30 to moveanteriorly, i.e., in the direction of its pre-herniated borders. Onceherniated segment 30 is in the desired position, connection member 3 issecured in a permanent fashion between anchor 1 and support member 2.This maintains tension between anchor 1 and support member 2 andrestricts motion of the herniated segment to within the pre-herniatedborders 40 of the disc. Support member 2 is used to anchor to herniatedsegment 30, support a weakened AF in which no visual evidence ofherniation is apparent, and may also be used to close a defect in the AFin the vicinity of herniated segment 30.

Anchor 1 is depicted in a representative form, as it can take one ofmany suitable shapes, be made from one of a variety of biocompatiblematerials, and be constructed so as to fall within a range of stiffness.It can be a permanent device constructed of durable plastic or metal orcan be made from a resorbable material such as polylactic acid (PLA) orpolyglycolic acid (PGA). Specific embodiments are not shown, but manypossible designs would be obvious to anyone skilled in the art.Embodiments include, but are not limited to, a barbed anchor made of PLAor a metal coil that can be screwed into the anterior AF. Anchor 1 canbe securely established within a portion of the functional spine unit inthe usual and customary manner for such devices and locations, such asbeing screwed into bone, sutured into tissue or bone, or affixed totissue or bone using an adhesive method, such as cement, or othersuitable surgical adhesives. Once established within the bone or tissue,anchor 1 should remain relatively stationary within the bone or tissue.

Support member 2 is also depicted in a representative format and sharesthe same flexibility in material and design as anchor 1. Both deviceelements can be of the same design, or they can be of different designs,each better suited to being established in healthy and diseased tissuerespectively. Alternatively, in other forms, support member 2 can be acap or a bead shape, which also serves to secure a tear or puncture inthe AF, or it can be bar or plate shaped, with or without barbs tomaintain secure contact with the herniated segment. Support member 2 canbe established securely to, within, or posterior to the herniatedsegment.

The anchor and support member can include suture, bone anchors, softtissue anchors, tissue adhesives, and materials that support tissueingrowth although other forms and materials are possible. They may bepermanent devices or resorbable. Their attachment to a portion of FSUand herniated segment must be strong enough to resist the tensionalforces that result from repair of the hernia and the loads generatedduring daily activities.

Connection member 3 is also depicted in representative fashion. Member 3may be in the format of a flexible filament, such as a single ormulti-strand suture, wire, or perhaps a rigid rod or broad band ofmaterial, for example. The connection member can further include suture,wire, pins, and woven tubes or webs of material. It can be constructedfrom a variety of materials, either permanent or resorbable, and can beof any shape suitable to fit within the confines of the intervertebraldisc space. The material chosen is preferably adapted to be relativelystiff while in tension, and relatively flexible against all other loads.This allows for maximal mobility of the herniated segment relative tothe anchor without the risk of the supported segment moving outside ofthe pre-herniated borders of the disc. The connection member may be anintegral component of either the anchor or support member or a separatecomponent. For example, the connection member and support member couldbe a length of non-resorbing suture that is coupled to an anchor,tensioned against the anchor, and sewn to the herniated segment.

FIGS. 3A and 3B depict another embodiment of device 13. In FIG. 3A theelements of the herniation constraining device are shown in positionprior to securing a herniated segment. Anchor 1 is positioned in the AFand connection member 3 is attached to anchor 1. Support member 4 ispositioned posterior to the posterior-most aspect of herniated segment30. In this way, support member 4 does not need to be secured inherniated segment 30 to cause herniated segment 30 to move within thepre-herniated borders 40 of the disc. Support member 4 has the sameflexibility in design and material as anchor 1, and may further take theform of a flexible patch or rigid plate or bar of material that iseither affixed to the posterior aspect of herniated segment 30 or issimply in a form that is larger than any hole in the AF directlyanterior to support member 4. FIG. 3B shows the positions of theelements of the device when tension is applied between anchor 1 andsupport member 4 along connection member 3. The herniated segment isdisplaced anteriorly, within the pre-herniated borders 40 of the disc.

FIGS. 4A and 4B show five examples of suitable anchoring sites withinthe FSU for anchor 1. FIG. 4A shows an axial view of anchor 1 in variouspositions within the anterior and lateral AF. FIG. 4B similarly shows asagittal view of the various acceptable anchoring sites for anchor 1.Anchor 1 is secured in the superior vertebral body 50, inferiorvertebral body 50′ or anterior AF 10, although any site that canwithstand the tension between anchor 1 and support member 2 alongconnection member 3 to support a herniated segment within itspre-herniated borders 40 is acceptable.

Generally, a suitable position for affixing one or more anchors is alocation anterior to the herniated segment such that, when tension isapplied along connection member 3, herniated segment 30 is returned to asite within the pre-herniated borders 40. The site chosen for the anchorshould be able to withstand the tensile forces applied to the anchorwhen the connection member is brought under tension. Because mostsymptomatic herniations occur in the posterior or posterior lateraldirections, the preferable site for anchor placement is anterior to thesite of the herniation. Any portion of the involved FSU is generallyacceptable, however the anterior, anterior medial, or anterior lateralAF is preferable. These portions of the AF have been shown to haveconsiderably greater strength and stiffness than the posterior orposterior lateral portions of the AF. As shown in FIGS. 4A and 4B,anchor 1 can be a single anchor in any of the shown locations, or therecan be multiple anchors 1 affixed in various locations and connected toa support member 2 to support the herniated segment. Connection member 3can be one continuous length that is threaded through the sited anchorsand the support member, or it can be several individual strands ofmaterial each terminated under tension between one or more anchors andone or more support members.

In various forms of the invention, the anchor(s) and connectionmember(s) may be introduced and implanted in the patient, with theconnection member under tension. Alternatively, those elements may beinstalled, without introducing tension to the connection member, butwhere the connection member is adapted to be under tension when thepatient is in a non-horizontal position, e.g., resulting from loading inthe intervertebral disc.

FIGS. 5A-C show an alternate embodiment of herniation constrainingdevice 13A. In this series of figures, device 13A, a substantiallyone-piece construct, is delivered through a delivery tube 6, althoughdevice 13A could be delivered in a variety of ways including, but notlimited to, by hand or by a hand held grasping instrument. In FIG. 5A,device 13A in delivery tube 6 is positioned against herniated segment30. In FIG. 5B, the herniated segment is displaced within itspre-herniated borders 40 by device 13A and/or delivery tube 6 such thatwhen, in FIG. 5C, device 13A has been delivered through delivery tube 6,and secured within a portion of the FSU, the device supports thedisplaced herniated segment within its pre-herniated border 40.Herniation constraining device 13A can be made of a variety of materialsand have one of many possible forms so long as it allows support of theherniated segment 30 within the pre-herniated borders 40 of the disc.Device 13A can anchor the herniated segment 30 to any suitable anchoringsite within the FSU, including, but not limited to the superiorvertebral body, inferior vertebral body, or anterior AF. Device 13A maybe used additionally to close a defect in the AF of herniated segment30. Alternatively, any such defect may be left open or may be closedusing another means.

FIG. 6 depicts the substantially one-piece device 13A supporting aweakened segment 30′ of the posterior AF 10′. Device 13A is positionedin or posterior to the weakened segment 30′ and secured to a portion ofthe FSU, such as the superior vertebral body 50, shown in the figure, orthe inferior vertebral body 50′ or anterior or anterior-lateral anulusfibrosis 10. In certain patients, there may be no obvious herniationfound at surgery. However, a weakened or torn AF that may not beprotruding beyond the pre-herniated borders of the disc may still inducethe surgeon to remove all or part of the NP in order to decrease therisk of herniation. As an alternative to discectomy, any of theembodiments of the invention may be used to support and perhaps closedefects in weakened segments of AF.

A further embodiment of the present invention involves augmentation ofthe soft tissues of the intervertebral disc to avoid or reverse discheight loss. FIGS. 7A and 7B show one embodiment of device 13 securingaugmentation material in the intervertebral disc space 55. In the leftside of FIG. 7A, anchors 1 have been established in the anterior AF 10.Augmentation material 7 is in the process of being inserted into thedisc space along connection member 3 which, in this embodiment, haspassageway 9. Support member 2′ is shown ready to be attached toconnection member 3 once the augmentation material 7 is properlysituated. In this embodiment, connection member 3 passes through anaperture 11 in support member 2′, although many other methods ofaffixing support member 2′ to connection member 3 are possible andwithin the scope of this invention.

Augmentation material 7 may have a passageway 9, such as a channel, slitor the like, which allows it to slide along the connection member 3, oraugmentation material 7 may be solid, and connection member 3 can bethreaded through augmentation material by means such as needle or otherpuncturing device. Connection member 3 is affixed at one end to anchor 1and terminated at its other end by a support member 2′, one embodimentof which is shown in the figure in a cap-like configuration. Supportmember 2′ can be affixed to connection member 3 in a variety of ways,including, but not limited to, swaging support member 2′ to connectionmember 3. In a preferred embodiment, support member 2′ is in a capconfiguration and has a dimension (diameter or length and width) largerthan the optional passageway 9, which serves to prevent augmentationmaterial 7 from displacing posteriorly with respect to anchor 1. Theright half of the intervertebral disc of FIG. 7A (axial view) and FIG.7B (sagittal view) show augmentation material 7 that has been implantedinto the disc space 55 along connection member 3 where it supports thevertebral bodies 50 and 50′. FIG. 7A shows an embodiment in whichsupport member 2′ is affixed to connection member 3 and serves only toprevent augmentation material 7 from moving off connection member 3. Theaugmentation device is free to move within the disc space. FIG. 7B showsan alternate embodiment in which support member 2′ is embedded in a sitein the functional spine unit, such as a herniated segment or posterioranulus fibrosis, to further restrict the movement of augmentationmaterial 7 or spacer material within the disc space.

Augmentation or spacer material can be made of any biocompatible,preferably flexible, material. Such a flexible material is preferablyfibrous, like cellulose or bovine or autologous collagen. Theaugmentation material can be plug or disc shaped. It can further becube-like, ellipsoid, spheroid or any other suitable shape. Theaugmentation material can be secured within the intervertebral space bya variety of methods, such as but not limited to, a suture loop attachedto, around, or through the material, which is then passed to the anchorand support member.

FIGS. 8, 9A, 9B and 10A and 10B depict further embodiments of the discherniation constraining device 13B in use for augmenting soft tissue,particularly tissue within the intervertebral space. In the embodimentsshown in FIGS. 8 and 9A, device 13B is secured within the intervertebraldisc space providing additional support for NP 20. Anchor 1 is securelyaffixed in a portion of the FSU, (anterior AF 10 in these figures).Connection member 3 terminates at support member 2, preventingaugmentation material 7 from migrating generally posteriorly withrespect to anchor 1. Support member 2 is depicted in these figures asestablished in various locations, such as the posterior AF 10′ in FIG.8, but support member 2 may be anchored in any suitable location withinthe FSU, as described previously. Support member 2 may be used to closea defect in the posterior AF. It may also be used to displace aherniated segment to within the pre-herniated borders of the disc byapplying tension between anchoring means 1 and 2 along connection member3.

FIG. 9A depicts anchor 1, connection member 3, spacer material 7 andsupport member 2′ (shown in the “cap”-type configuration) inserted as asingle construct and anchored to a site within the disc space, such asthe inferior or superior vertebral bodies. This configuration simplifiesinsertion of the embodiments depicted in FIGS. 7 and 8 by reducing thenumber of steps to achieve implantation. Connection member 3 ispreferably relatively stiff in tension, but flexible against all otherloads. Support member 2′ is depicted as a bar element that is largerthan passageway 9 in at least one plane.

FIG. 9B depicts a variation on the embodiment depicted in FIG. 9A. FIG.9B shows substantially one-piece disc augmentation device 13C, securedin the intervertebral disc space. Device 13C has anchor 1, connectionmember 3 and augmentation material 7. Augmentation material 7 and anchor1 could be pre-assembled prior to insertion into the disc space 55 as asingle construct. Alternatively, augmentation material 7 could beinserted first into the disc space and then anchored to a portion of theFSU by anchor 1.

FIGS. 10A and 10B show yet another embodiment of the disclosedinvention, 13D. In FIG. 10A, two connection members 3 and 3′ areattached to anchor 1. Two plugs of augmentation material 7 and 7′ areinserted into the disc space along connection members 3 and 3′.Connection members 3 and 3′ are then bound together (e.g., knottedtogether, fused, or the like). This forms loop 3″ that serves to preventaugmentation materials 7 and 7′ from displacing posteriorly. FIG. 10Bshows the position of the augmentation material 7 after it is secured bythe loop 3″ and anchor 1. Various combinations of augmentation material,connecting members and anchors can be used in this embodiment, such asusing a single plug of augmentation material, or two connection membersleading from anchor 1 with each of the connection members being bound toat least one other connection member. It could further be accomplishedwith more than one anchor with at least one connection member leadingfrom each anchor, and each of the connection members being bound to atleast one other connection member.

Any of the devices described herein can be used for closing defects inthe AF whether created surgically or during the herniation event. Suchmethods may also involve the addition of biocompatible material toeither the AF or NP. This material could include sequestered or extrudedsegments of the NP found outside the pre-herniated borders of the disc.

FIGS. 11-15 illustrate devices used in and methods for closing a defectin an anulus fibrosis. One method involves the insertion of a barrier orbarrier means 12 into the disc 15. This procedure can accompany surgicaldiscectomy. It can also be done without the removal of any portion ofthe disc 15 and further in combination with the insertion of anaugmentation material or device into the disc 15.

The method consists of inserting the barrier 12 into the interior of thedisc 15 and positioning it proximate to the interior aspect of theanulus defect 16. The barrier material is preferably considerably largerin area than the size of the defect 16, such that at least some portionof the barrier means 12 abuts healthier anulus fibrosis 10. The deviceacts to seal the anulus defect 16, recreating the closed isobaricenvironment of a healthy disc nucleus 20. This closure can be achievedsimply by an over-sizing of the implant relative to the defect 16. Itcan also be achieved by affixing the barrier means 12 to tissues withinthe functional spinal unit. In one embodiment of the present invention,the barrier 12 is affixed to the anulus surrounding the anulus defect16. This can be achieved with sutures, staples, glues or other suitablefixation means or fixation device 14. The barrier means 12 can also belarger in area than the defect 16 and be affixed to a tissue orstructure opposite the defect 16, e.g., anterior tissue in the case of aposterior defect.

The barrier means 12 is preferably flexible in nature. It can beconstructed of a woven material such as Dacron™ or Nylon™, a syntheticpolyamide or polyester, a polyethylene, and can further be an expandedmaterial, such as expanded polytetrafluroethylene (e-PTFE), for example.The barrier means 12 can also be a biologic material such ascross-linked collagen or cellulous.

The barrier means 12 can be a single piece of material. It can have anexpandable means or component that allows it to be expanded from acompressed state after insertion into the interior of the disc 15. Thisexpandable means can be active, such as a balloon, or passive, such as ahydrophilic material. The expandable means can also be a self-expandingelastically deforming material, for example.

FIGS. 11 and 12 illustrate a barrier 12 mounted within an anulus 10 andcovering an anulus defect 16. The barrier 12 can be secured to theanulus 10 with a fixation mechanism or fixation means 14. The fixationmeans 14 can include a plurality of suture loops placed through thebarrier 12 and the anulus 10. Such fixation can prevent motion orslipping of the barrier 12 away from the anulus defect 16.

The barrier means 12 can also be anchored to the disc 15 in multiplelocations. In one preferred embodiment, shown in FIGS. 13 and 14, thebarrier means 12 can be affixed to the anulus tissue 10 in orsurrounding the defect and further affixed to a secondary fixation siteopposite the defect, e.g. the anterior anulus 10 in a posteriorherniation, or the inferior 50′ or superior 50 vertebral body. Forexample, fixation means 14 can be used to attach the barrier 12 to theanulus 10 near the defect 16, while an anchoring mechanism 18 can securethe barrier 12 to a secondary fixation site. A connector 22 can attachthe barrier 12 to the anchor 18. Tension can be applied between theprimary and secondary fixation sites through a connector 22 so as tomove the anulus defect 16 toward the secondary fixation site. This maybe particularly beneficial in closing defects 16 that result inposterior herniations. By using this technique, the herniation can bemoved and supported away from any posterior neural structures whilefurther closing any defect in the anulus 10.

The barrier means 12 can further be integral to a fixation means suchthat the barrier means affixes itself to tissues within the functionalspinal unit.

Any of the methods described above can be augmented by the use of asecond barrier or a second barrier means 24 placed proximate to theouter aspect of the defect 16 as shown in FIG. 15. The second barrier 24can further be affixed to the inner barrier means 12 by the use of afixation means 14 such as suture material.

FIGS. 16A and 16B depict intervertebral disc 15 comprising nucleuspulposus 20 and anulus fibrosis 10. Nucleus pulposus 20 forms a firstanatomic region and extra-discal space 500 (any space exterior to thedisc) forms a second anatomic region wherein these regions are separatedby anulus fibrosis 10.

FIG. 16A is an axial (transverse) view of the intervertebral disc. Aposterior lateral defect 16 in anulus fibrosis 10 has allowed a segment30 of nucleus pulposus 20 to herniate into an extra discal space 500.Interior aspect 32 and exterior aspect 34 are shown, as are the right70′ and left 70 transverse processes and posterior process 80.

FIG. 16B is a sagittal section along the midline intervertebral disc.Superior pedicle 90 and inferior pedicle 90′ extend posteriorly fromsuperior vertebral body 95 and inferior vertebral body 95′ respectively.

To prevent further herniation of the nucleus 20 and to repair anypresent herniation, in a preferred embodiment, a barrier or barriermeans 12 can be placed into a space between the anulus 10 and thenucleus 20 proximate to the inner aspect 32 of defect 16, as depicted inFIGS. 17 and 18. The space can be created by blunt dissection.Dissection can be achieved with a separate dissection instrument, withthe barrier means 12 itself, or a combined dissection/barrier deliverytool 100. This space is preferably no larger than the barrier means suchthat the barrier means 12 can be in contact with both anulus 10 andnucleus 20. This allows the barrier means 12 to transfer load from thenucleus 20 to the anulus 10 when the disc is pressurized duringactivity.

In position, the barrier means 12 preferably spans the defect 16 andextends along the interior aspect 36 of the anulus 10 until it contactshealthy tissues on all sides of the defect 16, or on a sufficient extentof adjacent healthy tissue to provide adequate support under load.Healthy tissue may be non-diseased tissue and/or load bearing tissue,which may be micro-perforated or non-perforated. Depending on the extentof the defect 16, the contacted tissues can include the anulus 10,cartilage overlying the vertebral endplates, and/or the endplatesthemselves.

In the preferred embodiment, the barrier means 12 comprises twocomponents—a sealing means or sealing component 51 and an enlargingmeans or enlarging component 53, shown in FIGS. 21A and 21B.

The sealing means 51 forms the periphery of the barrier 12 and has aninterior cavity 17. There is at least one opening 8 leading into cavity17 from the exterior of the sealing means 51. Sealing means 51 ispreferably compressible or collapsible to a dimension that can readilybe inserted into the disc 15 through a relatively small hole. This holecan be the defect 16 itself or a site remote from the defect 16. Thesealing means 51 is constructed from a material and is formed in such amanner as to resist the passage of fluids and other materials aroundsealing means 51 and through the defect 16. The sealing means 51 can beconstructed from one or any number of a variety of materials including,but not limited to PTFE, e-PTFE, Nylon™, Marlex™, high-densitypolyethylene, and/or collagen. The thickness of the sealing componenthas been found to be optimal between about 0.001 inches (0.127 mm) and0.063 inches (1.6 mm).

The enlarging means 53 can be sized to fit within cavity 17 of sealingmeans 51. It is preferably a single object of a dimension that can beinserted through the same defect 16 through which the sealing means 51was passed. The enlarging means 53 can expand the sealing means 51 to anexpanded state as it is passed into cavity 17. One purpose of enlargingmeans 53 is to expand sealing means 51 to a size greater than that ofthe defect 16 such that the assembled barrier 12 prevents passage ofmaterial through the defect 16. The enlarger 53 can further impartstiffness to the barrier 12 such that the barrier 12 resists thepressures within nucleus pulposus 20 and expulsion through the defect16. The enlarging means 53 can be constructed from one or any number ofmaterials including, but not limited to, silicon rubber, variousplastics, stainless steel, nickel titanium alloys, or other metals.These materials may form a solid object, a hollow object, coiled springsor other suitable forms capable of filling cavity 17 within sealingmeans 51.

The sealing means 51, enlarging means 53, or the barrier means 12constructs can further be affixed to tissues either surrounding thedefect 16 or remote from the defect 16. In the preferred embodiment, noaspect of a fixation means or fixation device or the barrier means 12nor its components extend posterior to the disc 15 or into theextradiscal region 500, avoiding the risk of contacting and irritatingthe sensitive nerve tissues posterior to the disc 15.

In a preferred embodiment, the sealing means 51 is inserted into thedisc 15 proximate the interior aspect 36 of the defect. The sealingmeans 51 is then affixed to the tissues surrounding the defect using asuitable fixation means, such as suture or a soft-tissue anchor. Thefixation procedure is preferably performed from the interior of thesealing means cavity 17 as depicted in FIGS. 19 and 20. A fixationdelivery instrument 110 is delivered into cavity 17 through opening 8 inthe sealing means 51. Fixation devices 14 can then be deployed through awall of the sealing means 53 into surrounding tissues. Once the fixationmeans 14 have been passed into surrounding tissue, the fixation deliveryinstrument 110 can be removed from the disc 15. This method eliminatesthe need for a separate entryway into the disc 15 for delivery offixation means 14. It further minimizes the risk of material leakingthrough sealing means 51 proximate to the fixation means 14. One or morefixation means 14 can be delivered into one or any number of surroundingtissues including the superior 95 and inferior 95′ vertebral bodies.Following fixation of the sealing means 51, the enlarging means 53 canbe inserted into cavity 17 of the sealing means 51 to further expand thebarrier means 12 construct as well as increase its stiffness, asdepicted in FIGS. 21A and 21B. The opening 8 into the sealing means 51can then be closed by a suture or other means, although this is not arequirement of the present invention. In certain cases, insertion of aseparate enlarging means may not be necessary if adequate fixation ofthe sealing means 51 is achieved.

Another method of securing the barrier 12 to tissues is to affix theenlarging means 53 to tissues either surrounding or remote from thedefect 16. The enlarging means 53 can have an integral fixation region 4that facilitates securing it to tissues as depicted in FIGS. 22A, 22B,32A and 43B. This fixation region 4 can extend exterior to sealing means51 either through opening 8 or through a separate opening. Fixationregion 4 can have a hole through which a fixation means or fixationdevice 14 can be passed. In a preferred embodiment, the barrier 12 isaffixed to at least one of the surrounding vertebral bodies (95 and 95′)proximate to the defect using a bone anchor 14′. The bone anchor 14′ canbe deployed into the vertebral bodies 50, 50′ at some angle between 0Eand 180E relative to a bone anchor deployment tool. As shown the boneanchor 14′ is mounted at 90E relative to the bone anchor deploymenttool. Alternatively, the enlarging means 53 itself can have an integralfixation device 14 located at a site or sites along its length.

Another method of securing the barrier means 12 is to insert the barriermeans 12 through the defect 16 or another opening into the disc 15,position it proximate to the interior aspect 36 of the defect 16, andpass at least one fixation means 14 through the anulus 10 and into thebarrier 12. In a preferred embodiment of this method, the fixation means14 can be darts 15 and are first passed partially into anulus 10 withina fixation device 120, such as a hollow needle. As depicted in FIGS. 23Aand 23B, fixation means 25 can be advanced into the barrier means 12 andfixation device 120 removed. Fixation means 25 preferably have two ends,each with a means to prevent movement of that end of the fixationdevice. Using this method, the fixation means can be lodged in both thebarrier 12 and anulus fibrosis 10 without any aspect of fixation means25 exterior to the disc in the extradiscal region 500.

In several embodiments of the present invention, the barrier (or“patch”) 12 can be placed between two neighboring layers 33, 37(lamellae) of the anulus 10 on either or both sides of the defect 16 asdepicted in FIGS. 24A and 24B. FIG. 24A shows an axial view while 24Bshows a sagittal cross section. Such positioning spans the defect 16.The barrier means 12 can be secured using the methods outlined.

A dissecting tool can be used to form an opening extendingcircumferentially 31 within the anulus fibrosis such that the barriercan be inserted into the opening. Alternatively, the barrier itself canhave a dissecting edge such that it can be driven at least partiallyinto the sidewalls of defect 16, annulotomy 416, access hole 417 oropening in the anulus. This process can make use of the naturallylayered structure in the anulus in which adjacent layers 33, 37 aredefined by a circumferentially extending boundary 35 between the layers.

Another embodiment of the barrier 12 is a patch having a length,oriented along the circumference of the disc, which is substantiallygreater than its height, which is oriented along the distance separatingthe surrounding vertebral bodies. A barrier 12 having a length greaterthan its height is illustrated in FIG. 25. The barrier 12 can bepositioned across the defect 16 as well as the entirety of the posterioraspect of the anulus fibrosis 10. Such dimensions of the barrier 12 canhelp to prevent the barrier 12 from slipping after insertion and can aidin distributing the pressure of the nucleus 20 evenly along theposterior aspect of the anulus 10.

The barrier 12 can be used in conjunction with an augmentation device 11inserted within the anulus 10. The augmentation device 11 can includeseparate augmentation devices 42 as shown in FIG. 26. The augmentationdevice 11 can also be a single augmentation device 44 and can form partof the barrier 12 as barrier region 300, coiled within the anulusfibrosis 10, as shown in FIG. 27. Either the barrier 12 or barrierregion 300 can be secured to the tissues surrounding the defect 16 byfixation devices or darts 25, or be left unconstrained

In another embodiment of the present invention, the barrier or patch 12may be used as part of a method to augment the intervertebral disc. Inone aspect of this method, augmentation material or devices are insertedinto the disc through a defect (either naturally occurring or surgicallygenerated). Many suitable augmentation materials and devices arediscussed above and in the prior art. As depicted in FIG. 26, thebarrier means is then inserted to aid in closing the defect and/or toaid in transferring load from the augmentation materials/devices tohealthy tissues surrounding the defect. In another aspect of thismethod, the barrier means is an integral component to an augmentationdevice. As shown in FIGS. 27, 28A and 28B, the augmentation portion maycomprise a length of elastic material that can be inserted linearlythrough a defect in the anulus. A region 300 of the length forms thebarrier means of some embodiments of the present invention and can bepositioned proximate to the interior aspect of the defect once thenuclear space is adequately filled. Barrier region 300 may then beaffixed to surrounding tissues such as the AF and/or the neighboringvertebral bodies using any of the methods and devices described above.

FIGS. 28A and 28B illustrate axial and sagittal sections, respectively,of an alternate configuration of an augmentation device 38. In thisembodiment, barrier region 300 extends across the defect 16 and hasfixation region 4 facilitating fixation of the device 13 to superiorvertebral body 50 with anchor 14′.

FIGS. 29A-D illustrate the deployment of a barrier 12 from an entry site800 remote from the defect in the anulus fibrosis 10. FIG. 29A showsinsertion instrument 130 with a distal end positioned within the discspace occupied by nucleus pulposus 20. FIG. 29B depicts deliverycatheter 140 exiting the distal end of insertion instrument 130 withbarrier 12 on its distal end. Barrier 12 is positioned across theinterior aspect of the defect 16. FIG. 29C depicts the use of anexpandable barrier 12′ wherein delivery catheter 140 is used to expandthe barrier 12′ with balloon 150 on its distal end. Balloon 150 mayexploit heat to further adhere barrier 12′ to surrounding tissue. FIG.29D depicts removal of balloon 150 and delivery catheter 140 from thedisc space leaving expanded barrier means 12′ positioned across defect16.

Another method of securing the barrier means 12 is to adhere it tosurrounding tissues through the application of heat. In this embodiment,the barrier means 12 includes a sealing means 51 comprised of athermally adherent material that adheres to surrounding tissues upon theapplication of heat. The thermally adherent material can includethermoplastic, collagen, or a similar material. The sealing means 51 canfurther comprise a separate structural material that adds strength tothe thermally adherent material, such as a woven Nylon™ or Marlex™. Thisthermally adherent sealing means preferably has an interior cavity 17and at least one opening 8 leading from the exterior of the barriermeans into cavity 17. A thermal device can be attached to the insertioninstrument shown in FIGS. 29C and 29D. The insertion instrument 130having a thermal device can be inserted into cavity 17 and used to heatsealing means 51 and surrounding tissues. This device can be a simplethermal element, such as a resistive heating coil, rod or wire. It canfurther be a number of electrodes capable of heating the barrier meansand surrounding tissue through the application of radio frequency (RF)energy. The thermal device can further be a balloon 150, 150′, as shownin FIG. 47, capable of both heating and expanding the barrier means.Balloon 150, 150′ can either be inflated with a heated fluid or haveelectrodes located about its surface to heat the barrier means with RFenergy. Balloon 150, 150′ is deflated and removed after heating thesealing means. These thermal methods and devices achieve the goal ofadhering the sealing means to the AF and NP and potentially othersurrounding tissues. The application of heat can further aid theprocedure by killing small nerves within the AF, by causing the defectto shrink, or by causing cross-linking and/or shrinking of surroundingtissues. An expander or enlarging means 53 can also be an integralcomponent of barrier 12 inserted within sealing means 51. After theapplication of heat, a separate enlarging means 53 can be inserted intothe interior cavity of the barrier means to either enlarge the barrier12 or add stiffness to its structure. Such an enlarging means ispreferably similar in make-up and design to those described above. Useof an enlarging means may not be necessary in some cases and is not arequired component of this method.

The barrier means 12 shown in FIG. 25 preferably has a primary curvatureor gentle curve along the length of the patch or barrier 12 that allowsit to conform to the inner circumference of the AF 10. This curvaturemay have a single radius R as shown in FIGS. 44A and 44B or may havemultiple curvatures. The curvature can be fabricated into the barrier 12and/or any of its components. For example, the sealing means can be madewithout an inherent curvature while the enlarging means can have aprimary curvature along its length. Once the enlarging means is placedwithin the sealing means the overall barrier means assembly takes on theprimary curvature of the enlarging means. This modularity allowsenlarging means with specific curvatures to be fabricated for defectsoccurring in various regions of the anulus fibrosis.

The cross section of the barrier 12 can be any of a number of shapes.Each embodiment exploits a sealing means 51 and an enlarging means 53that may further add stiffness to the overall barrier construct. FIGS.30A and 30B show an elongated cylindrical embodiment with enlargingmeans 53 located about the long axis of the device. FIGS. 31A and 31Bdepict a barrier means comprising an enlarging means 53 with a centralcavity 49. FIGS. 32A and 32B depict a barrier means comprising anon-axisymmetric sealing means 51. In use, the longer section of sealingmeans 51 as seen on the left side of this figure would extend betweenopposing vertebra 50 and 50′. FIGS. 33A and 33B depict a barrier meanscomprising a non-axisymmetric sealing means 51 and enlarger 53. Theconcave portion of the barrier means preferably faces nucleus pulposus20 while the convex surface faces the defect 16, annulotomy 416, oraccess hole 417 and the inner aspect of the anulus fibrosis 10. Thisembodiment exploits pressure within the disc to compress sealing means51 against neighboring vertebral bodies 50 and 50′ to aid in sealing.The ‘C’ shape as shown in FIG. 33A is the preferred shape of the barrierwherein the convex portion of the patch rests against the interioraspect of the AF while the concave portion faces the NP. Used in thismanner, the barrier or patch 12 serves to partially encapsulate thenucleus puposus 20 by conforming to the gross morphology of the innersurface of the anulus 10 and presenting a concave or cupping surfacetoward the nucleus 20. To improve the sealing ability of such a patch,the upper and lower portions of this ‘C’ shaped barrier means arepositioned against the vertebral endplates or overlying cartilage. Asthe pressure within the nucleus increases, these portions of the patchare pressurized toward the endplates with an equivalent pressure,preventing the passage of materials around the barrier means. Dissectinga matching cavity prior to or during patch placement can facilitate useof such a ‘C’ shaped patch.

FIGS. 34 through 41 depict various enlarging or expansion devices 53that can be employed to aid in expanding a sealing element 51 within theintervertebral disc 15. Each embodiment can be covered by, coated with,or cover the sealing element 51. The sealing means 51 can further bewoven through the expansion means 53. The sealing element 51 or membranecan be a sealer which can prevent flow of a material from within theanulus fibrosis of the intervertebral disc through a defect in theanulus fibrosis. The material within the anulus can include nucleuspulposus or a prosthetic augmentation device, such as a hydrogel.

FIGS. 34 through 38 depict alternative patterns to that illustrated inFIG. 33A. FIG. 33A shows the expansion devices 53 within the sealingmeans 51. The sealing means can alternatively be secured to one oranother face (concave or convex) of the expansion means 53. This canhave advantages in reducing the overall volume of the barrier means 12,simplifying insertion through a narrow cannula. It can also allow thebarrier means 12 to induce ingrowth of tissue on one face and not theother. The sealing means 51 can be formed from a material that resistsingrowth such as expanded polytetraflouroethylene (e-PTFE). Theexpansion means 53 can be constructed of a metal or polymer thatencourages ingrowth. In several embodiments, if the e-PTFE sealing means51 is secured to the concave face of the expansion means 53, tissue cangrow into the expansion means 53 from outside of the disc 15, helping tosecure the barrier means 12 in place and seal against egress ofmaterials from within the disc 15.

The expansion means 53 shown in FIG. 33A can be inserted into thesealing means 51 once the sealing means 51 is within the disc 15.Alternatively, the expansion means 53 and sealing means 51 can beintegral components of the barrier means 12 that can be inserted as aunit into the disc.

The patterns shown in FIGS. 34 through 38 can preferably be formed froma relatively thin sheet of material. The material may be a polymer,metal, or gel, however, the superelastic properties of nickel titaniumalloy (NITINOL) makes this metal particularly advantageous in thisapplication. Sheet thickness can generally be in a range of about 0.1 mmto about 0.6 mm and for certain embodiments has been found to be optimalif between about 0.003″ to about 0.015″ (0.0762 mm to 0.381 mm), for thethickness to provide adequate expansion force to maintain contactbetween the sealing means 51 and surrounding vertebral endplates. Thepattern may be Wire Electro-Discharge Machined, cut by laser, chemicallyetched, or formed by other suitable means.

FIG. 34 shows an embodiment of a non-axisymmetric expander 153 having asuperior edge 166 and an inferior edge 168. The expander 153 can form aframe of barrier 12. This embodiment comprises dissecting surfaces orends 160, radial elements or fingers 162 and a central strut 164. Thecircular shape of the dissecting ends 160 aids in dissecting through thenucleus pulposus 20 and/or along or between an inner surface of theanulus fibrosis 10. The distance between the left-most and right-mostpoints on the dissecting ends is the expansion means length 170. Thislength 170 preferably lies along the inner perimeter of the posterioranulus following implantation. The expander length 170 can be as shortas about 3 mm and as long as the entire interior perimeter of the anulusfibrosis. The superior-inferior height of these dissecting ends 160 ispreferably similar to or larger than the posterior disc height.

This embodiment employs a multitude of fingers 162 to aid in holding aflexible sealer or membrane against the superior and inferior vertebralendplates. The distance between the superior-most point of the superiorfinger and the inferior-most point on the inferior finger is theexpansion means height 172. This height 172 is preferably greater thanthe disc height at the inner surface of the posterior anulus. Thegreater height 172 of the expander 153 allows the fingers 162 to deflectalong the superior and inferior vertebral endplates, enhancing the sealof the barrier means 12 against egress of material from within the disc15.

The spacing between the fingers 162 along the expander length 170 can betailored to provide a desired stiffness of the expansion means 153.Greater spacing between any two neighboring fingers 162 can further beemployed to insure that the fingers 170 do not touch if the expansionmeans 153 is required to take a bend along its length. The central strut164 can connect the fingers and dissecting ends and preferably liesalong the inner surface of the anulus 10 when seated within the disc 15.Various embodiments may employ struts 164 of greater or lesser heightsand thicknesses to vary the stiffness of the overall expansion means 153along its length 170 and height 172.

FIG. 35 depicts an alternative embodiment to the expander 153 of FIG.34. Openings or slots 174 can be included along the central strut 164.These slots 174 promote bending of the expander 153 and fingers 162along a central line 176 connecting the centers of the dissecting ends160. Such central flexibility has been found to aid against superior orinferior migration of the barrier means or barrier 12 when the barrier12 has not been secured to surrounding tissues.

FIGS. 34B and 34C depict different perspective views of a preferredembodiment of the expander/frame 153 within an intervertebral disc 15.Expander 53 is in its expanded condition and lies along and/or withinthe posterior wall 21 and extends around the lateral walls 23 of theanulus fibrosis 10. The superior 166 and inferior 168 facing fingers 162of expander 153 extend along the vertebral endplates (not shown) and/orthe cartilage overlying the endplates. The frame 153 can take on a 3-Dconcave shape in this preferred position with the concavity generallydirected toward the interior of the intervertebral disc and specificallya region occupied by the nucleus pulposus 20.

The bending stiffness of expander 153 can resist migration of theimplant from this preferred position within the disc 15. The principlebehind this stiffness-based stability is to place the regions ofexpander 153 with the greatest flexibility in the regions of the disc153 with the greatest mobility or curvature. These flexible regions ofexpander 153 are surrounded by significantly stiffer regions. Hence, inorder for the implant to migrate, a relatively stiff region of theexpander must move into a relatively curved or mobile region of thedisc.

For example, in order for expander 153 of FIG. 34B to move around theinner circumference of anulus fibrosis 10 (e.g., from the posterior wall21 onto the lateral 23 and/or anterior 27 wall), the stiff centralregion of expander 153 spanning the posterior wall 21 would have to bendaround the acute curves of the posterior lateral corners of anulus 10.The stiffer this section of expander 153 is, the higher the forcesnecessary to force it around these corners and the less likely it is tomigrate in this direction. This principle was also used in thisembodiment to resist migration of fingers 162 away from the vertebralendplates: The slots 174 cut along the length of expander 153 create acentral flexibility that encourages expander 153 to bend along an axisrunning through these slots as the posterior disc height increases anddecreased during flexion and extension. In order for the fingers 162 tomigrate away from the endplate, this central flexible region must moveaway from the posterior anulus 21 and toward an endplate. This motion isresisted by the greater stiffness of expander 153 in the areas directlyinferior and superior to this central flexible region.

The expander 153 is preferably covered by a membrane that acts tofurther restrict the movement of materials through the frame and towardthe outer periphery of the anulus fibrosis.

FIG. 36 depicts an embodiment of the expander 153 of FIG. 33A with anenlarged central strut 164 and a plurality of slots 174. This centralstrut 164 can have a uniform stiffness against superior-inferior 166 and168 bending as shown in this embodiment. The strut 164 can alternativelyhave a varying stiffness along its height 178 to either promote orresist bending at a given location along the inner surface of the anulus10.

FIGS. 37A-C depict a further embodiment of the frame or expander 153.This embodiment employs a central lattice 180 consisting of multiple,fine interconnected struts 182. Such a lattice 180 can provide astructure that minimizes bulging of the sealing means 51 underintradiscal pressures. The orientation and location of these struts 182have been designed to give the barrier 12 a bend-axis along the centralarea of the expander height 172. The struts 182 support inferior 168 andsuperior 166 fingers 162 similar to previously described embodiments.However, these fingers 162 can have varying dimensions and stiffnessalong the length of the barrier 12. Such fingers 162 can be useful forhelping the sealer 51 conform to uneven endplate geometries. FIG. 37Billustrates the curved cross section 184 of the expander 153 of FIG.37A. This curve 184 can be an arc segment of a circle as shown.Alternatively, the cross section can be an ellipsoid segment or have amultitude of arc segments of different radii and centers. FIG. 37C is aperspective view showing the three dimensional shape of the expander 153of FIGS. 37A and 37B.

The embodiment of the frame 153 as shown in FIGS. 37A-C, can also beemployed without the use of a covering membrane. The nucleus pulposus ofmany patients with low back pain or disc herniation can degenerate to astate in which the material properties of the nucleus cause it to behavemuch more like a solid than a gel. As humans age, the water content ofthe nucleus declines from roughly 88% to less than 75%. As this occurs,there is an increase in the cross linking of collagen within the discresulting in a greater solidity of the nucleus. When the pore size orthe largest open area of any given gap in the lattice depicted in FIGS.37A-37C is between about 0.05 mm² (7.75×10⁻⁵ in²) and about 0.75 mm²(1.16×10⁻³ in²), the nucleus pulposus is unable to extrude through thelattice at pressures generated within the disc (between about 250 KPaand about 1.8 MPa). The preferred pore size has been found to beapproximately 0.15 mm² (2.33×10⁻⁴ in²). This pore size can be used withany of the disclosed embodiments of the expander or any other expanderthat falls within the scope of embodiments of the invention to preventmovement of nucleus toward the outer periphery of the disc without theneed for an additional membrane. The membrane thickness is preferably ina range of about 0.025 mm to about 2.5 mm.

FIG. 38 depicts an expander 153 similar to that of FIG. 37A withoutfingers. The expander 153 includes a central lattice 180 consisting ofmultiple struts 182.

FIGS. 39 through 41 depict another embodiment of the expander 153 ofsome embodiments of the present invention. These tubular expanders canbe used in the barrier 12 embodiment depicted in FIG. 31A. The sealer 51can cover the expander 153 as shown in FIG. 31A. Alternatively, thesealer 51 can cover the interior surface of the expander or an arcsegment of the tube along its length on either the interior or exteriorsurface.

FIG. 39 depicts an embodiment of a tubular expander 154. The superior166 and inferior surfaces 168 of the tubular expander 154 can deployagainst the superior and inferior vertebral endplates, respectively. Thedistance 186 between the superior 166 and inferior 168 surfaces of theexpander 154 are preferably equal to or greater than the posterior discheight at the inner surface of the anulus 10. This embodiment has ananulus face 188 and nucleus face 190 as shown in FIGS. 39B, 39C and 39D.The anulus face 188 can be covered by the sealer 51 from the superior166 to inferior 168 surface of the expander 154. This face 188 liesagainst the inner surface of the anulus 10 in its deployed position andcan prevent egress of materials from within the disc 15. The primarypurpose of the nucleus face 190 is to prevent migration of the expander154 within the disc 15. The struts 192 that form the nucleus face 190can project anteriorly into the nucleus 20 when the barrier 12 ispositioned across the posterior wall of the anulus 10. This anteriorprojection can resist rotation of the tubular expansion means 154 aboutits long axis. By interacting with the nucleus 20, the struts 192 canfurther prevent migration around the circumference of the disc 15.

The struts 192 can be spaced to provide nuclear gaps 194. These gaps 194can encourage the flow of nucleus pulposus 20 into the interior of theexpander 154. This flow can insure full expansion of the barrier 12within the disc 15 during deployment.

The embodiments of FIGS. 39, 40 and 41 vary by their cross-sectionalshape. FIG. 39 has a circular cross section 196 as seen in FIG. 39C. Ifthe superior-inferior height 186 of the expander 154 is greater thanthat of the disc 15, this circular cross section 196 can deform into anoval when deployed, as the endplates of the vertebrae compress theexpander 154. The embodiment of the expander 154 shown in FIG. 40 ispreformed into an oval shape 198 shown in FIG. 40C. Compression by theendplates can exaggerate the unstrained oval 198. This oval 198 canprovide greater stability against rotation about a long axis of theexpander 154. The embodiment of FIGS. 41B, 41C and 41D depict an‘egg-shaped’ cross section 202, as shown in FIG. 41C, that can allowcongruity between the curvature of the expander 154 and the inner wallof posterior anulus 10. Any of a variety of alternate cross sectionalshapes can be employed to obtain a desired fit or expansion forcewithout deviating from the spirit of the present invention.

FIGS. 40E, 40F, and 40I depict the expander 154 of FIGS. 40A-D having asealing means 51 covering the exterior surface of the anulus face 188.This sealing means 51 can be held against the endplates and the innersurface of the posterior anulus by the expander 154 in its deployedstate.

FIGS. 40G and 40H depict the expander 154 of FIG. 40B with a sealer 51covering the interior surface of the anulus face 188. This position ofthe sealer 51 can allow the expander 154 to contact both the vertebralendplates and inner surface of the posterior anulus. This can promoteingrowth of tissue into the expander 154 from outside the disc 15.Combinations of sealer 51 that cover all or part of the expander 154 canalso be employed without deviating from the scope of the presentinvention. The expander 154 can also have a small pore size therebyallowing retention of a material such as a nucleus pulposus, forexample, without the need for a sealer as a covering.

FIGS. 42A-D depict cross sections of a preferred embodiment of sealingmeans 51 and enlarging means 53. Sealing means 51 has internal cavity 17and opening 8 leading from its outer surface into internal cavity 17.Enlarger 53 can be inserted through opening 8 and into internal cavity17.

FIGS. 43A and 43B depict an alternative configuration of enlarger 53.Fixation region 4 extends through opening 8 in sealing means 51.Fixation region 4 has a through-hole that can facilitate fixation ofenlarger 53 to tissues surrounding defect 16.

FIGS. 44A and 44B depict an alternative shape of the barrier. In thisembodiment, sealing means 51, enlarger 53, or both have a curvature withradius R. This curvature can be used in any embodiment of the presentinvention and may aid in conforming to the curved inner circumference ofanulus fibrosis 10.

FIG. 45 is a section of a device used to affix sealing means 51 totissues surrounding a defect. In this figure, sealing means 51 would bepositioned across interior aspect 50 of defect 16. The distal end ofdevice 110′ would be inserted through defect 16 and opening 8 into theinterior cavity 17. On the right side of this figure, fixation dart 25has been passed from device 110′, through a wall of sealing means 51 andinto tissues surrounding sealing means 51. On the right side of thefigure, fixation dart 25 is about to be passed through a wall of sealingmeans 51 by advancing pusher 111 relative to device 110′ in thedirection of the arrow.

FIG. 46 depicts the use of thermal device 200 to heat sealing means 51and adhere it to tissues surrounding a defect. In this figure, sealingmeans 51 would be positioned across the interior aspect 36 of a defect16. The distal end of thermal device 200 would be inserted through thedefect and opening 8 into interior cavity 17. In this embodiment,thermal device 200 employs at its distal end resistive heating element210 connected to a voltage source by wires 220. Covering 230 is anon-stick surface such as Teflon tubing that ensures the ability toremove device 200 from interior cavity 17. In this embodiment, device200 would be used to heat first one half, and then the other half ofsealing means 51.

FIG. 47 depicts an expandable thermal element, such as a balloon, thatcan be used to adhere sealing means 51 to tissues surrounding a defect.As in FIG. 18, the distal end of device 130 can be inserted through thedefect and opening 8 into interior cavity 17, with balloon 150′ on thedistal end device 130 in a collapsed state. Balloon 150′ is theninflated to expanded state 150, expanding sealing means 51. Expandedballoon 150 can heat sealing means 51 and surrounding tissues byinflating it with a heated fluid or by employing RF electrodes. In thisembodiment, device 130 can be used to expand and heat first one half,then the other half of sealing means 51.

FIG. 48 depicts an alternative embodiment to device 130. This deviceemploys an elongated, flexible balloon 150′ that can be inserted intoand completely fill internal cavity 17 of sealing means 51 prior toinflation to an expanded state 150. Using this embodiment, inflation andheating of sealing means 51 can be performed in one step.

FIGS. 49A through 49G illustrate a method of implanting an intradiscalimplant. An intradiscal implant system consists of an intradiscalimplant 400, a delivery device or cannula 402, an advancer 404 and atleast one control filament 406. The intradiscal implant 400 is loadedinto the delivery cannula 402 which has a proximal end 408 and a distalend 410. FIG. 49A illustrates the distal end 410 advanced into the disc15 through an annulotomy 416. This annulotomy 416 can be through anyportion of the anulus 10, but is preferably at a site proximate to adesired, final implant location. The implant 400 is then pushed into thedisc 15 through the distal end 410 of the cannula 402 in a directionthat is generally away from the desired, final implant location as shownin FIG. 49B. Once the implant 400 is completely outside of the deliverycannula 402 and within the disc 15, the implant 400 can be pulled intothe desired implant location by pulling on the control filament 406 asshown in FIG. 49C. The control filament 406 can be secured to theimplant 400 at any location on or within the implant 400, but ispreferably secured at least at a site 414 or sites on a distal portion412 of the implant 400, e.g., that portion that first exits the deliverycannula 402 when advanced into the disc 15. These site or sites 414 aregenerally furthest from the desired, final implant location once theimplant has been fully expelled from the interior of the deliverycannula 402.

Pulling on the control filament 406 causes the implant 400 to movetoward the annulotomy 416. The distal end 410 of the delivery cannula402 can be used to direct the proximal end 420 of the implant 400 (thatportion of the implant 400 that is last to be expelled from the deliverycannula 402) away from the annulotomy 416 and toward an inner aspect ofthe anulus 10 nearest the desired implant location. Alternately, theadvancer 404 can be used to position the proximal end of the implanttoward an inner aspect of the anulus 20 near the implant location, asshown in FIG. 49E. Further pulling on the control filament 406 causesthe proximal end 426 of the implant 400 to dissect along the inneraspect of the anulus 20 until the attachment site 414 or sites of theguide filament 406 to the implant 400 has been pulled to the inneraspect of the annulotomy 416, as shown in FIG. 49D. In this way, theimplant 400 will extend at least from the annulotomy 416 and along theinner aspect of the anulus 10 in the desired implant location,illustrated in FIG. 49F.

The implant 400 can be any one of the following (including a combinationof two or more of the following): nucleus replacement device, nucleusaugmentation device, anulus augmentation device, anulus replacementdevice, the barrier of the present invention or any of its components,drug carrier device, carrier device seeded with living cells, or adevice that stimulates or supports fusion of the surrounding vertebra.The implant 400 can be a membrane which prevents the flow of a materialfrom within the anulus fibrosis of an intervertebral disc through adefect in the disc. The material within the anulus fibrosis can be, forexample, a nucleus pulposus or a prosthetic augmentation device, such ashydrogel. The membrane can be a sealer. The implant 400 can be wholly orpartially rigid or wholly or partially flexible. It can have a solidportion or portions that contain a fluid material. It can comprise asingle or multitude of materials. These materials can include metals,polymers, gels and can be in solid or woven form. The implant 400 caneither resist or promote tissue ingrowth, whether fibrous or bony.

The cannula 402 can be any tubular device capable of advancing theimplant 400 at least partially through the anulus 10. It can be made ofany suitable biocompatible material including various known metals andpolymers. It can be wholly or partially rigid or flexible. It can becircular, oval, polygonal, or irregular in cross section. It must havean opening at least at its distal end 410, but can have other openingsin various locations along its length.

The advancer 404 can be rigid or flexible, and have one of a variety ofcross sectional shapes either like or unlike the delivery cannula 402.It may be a solid or even a column of incompressible fluid, so long asit is stiff enough to advance the implant 400 into the disc 15. Theadvancer 404 can be contained entirely within the cannula 402 or canextend through a wall or end of the cannula to facilitate manipulation.

Advancement of the implant 400 can be assisted by various levers, gears,screws and other secondary assist devices to minimize the force requiredby the surgeon to advance the implant 400. These secondary devices canfurther give the user greater control over the rate and extent ofadvancement into the disc 15.

The guide filament 406 may be a string, rod, plate, or other elongateobject that can be secured to and move with the implant 400 as it isadvanced into the disc 15. It can be constructed from any of a varietyof metals or polymers or combination thereof and can be flexible orrigid along all or part of its length. It can be secured to a secondaryobject 418 or device at its end opposite that which is secured to theimplant 400. This secondary device 418 can include the advancer 404 orother object or device that assists the user in manipulating thefilament. The filament 406 can be releasably secured to the implant 400,as shown in FIG. 49G or permanently affixed. The filament 406 can belooped around or through the implant. Such a loop can either be cut orhave one end pulled until the other end of the loop releases the implant400. It may be bonded to the implant 400 using adhesive, welding, or asecondary securing means such as a screw, staple, dart, etc. Thefilament 406 can further be an elongate extension of the implantmaterial itself. If not removed following placement of the implant, thefilament 406 can be used to secure the implant 400 to surroundingtissues such as the neighboring anulus 10, vertebral endplates, orvertebral bodies either directly or through the use of a dart, screw,staple, or other suitable anchor.

Multiple guide filaments can be secured to the implant 400 at variouslocations. In one preferred embodiment, a first or distal 422 and asecond or proximal 424 guide filament are secured to an elongate implant400 at or near its distal 412 and proximal 420 ends at attachment sites426 and 428, respectively. These ends 412 and 420 correspond to thefirst and last portions of the implant 400, respectively, to be expelledfrom the delivery cannula 402 when advanced into the disc 15. Thisdouble guide filament system allows the implant 400 to be positioned inthe same manner described above in the single filament technique, andillustrated in FIGS. 50A-C. However, following completion of this firsttechnique, the user may advance the proximal end 420 of the device 400across the annulotomy 416 by pulling on the second guide filament 424,shown in FIG. 50D. This allows the user to controllably cover theannulotomy 416. This has numerous advantages in various implantationprocedures. This step may reduce the risk of herniation of eithernucleus pulposus 20 or the implant itself. It may aid in sealing thedisc, as well as preserving disc pressure and the natural function ofthe disc. It may encourage ingrowth of fibrous tissue from outside thedisc into the implant. It may further allow the distal end of theimplant to rest against anulus further from the defect created by theannulotomy. Finally, this technique allows both ends of an elongateimplant to be secured to the disc or vertebral tissues.

Both the first 422 and second 424 guide filaments can be simultaneouslytensioned, as shown in FIG. 50E, to ensure proper positioning of theimplant 400 within the anulus 10. Once the implant 400 is placed acrossthe annulotomy, the first 422 and second 424 guide filaments can beremoved from the input 400, as shown in FIG. 50F. Additional controlfilaments and securing sites may further assist implantation and/orfixation of the intradiscal implants.

In another embodiment of the present invention, as illustrated in FIGS.51A-C, an implant guide 430 may be employed to aid directing the implant400 through the annulotomy 416, through the nucleus pulposus 10, and/oralong the inner aspect of the anulus 10. This implant guide 430 can aidin the procedure by dissecting through tissue, adding stiffness to theimplant construct, reducing trauma to the anulus or other tissues thatcan be caused by a stiff or abrasive implant, providing 3-D control ofthe implants orientation during implantation, expanding an expandableimplant, or temporarily imparting a shape to the implant that isbeneficial during implantation. The implant guide 430 can be affixed toeither the advancer 404 or the implant 406 themselves. In a preferredembodiment shown in FIGS. 52A and 52B, the implant guide 430 is securedto the implant 400 by the first 424 and second 426 guide filaments ofthe first 426 and the second 428 attachment sites, respectively. Theguide filaments 424 and 426 may pass through or around the implant guide430. In this embodiment, the implant guide 430 may be a thin, flat sheetof biocompatible metal with holes passing through its surface proximateto the site or sites 426 and 428 at which the guide filaments 422 and424 are secured to the implant 400. These holes allow passage of thesecuring filament 422 and 424 through the implant guide 430. Such anelongated sheet may run along the implant 400 and extend beyond itsdistal end 412. The distal end of the implant guide 430 may be shaped tohelp dissect through the nucleus 10 and deflect off of the anulus 10 asthe implant 400 is advanced into the disc 15. When used with multipleguide filaments, such an implant guide 430 can be used to controlrotational stability of the implant 400. It may also be used to retractthe implant 400 from the disc 15 should this become necessary. Theimplant guide 430 may also extend beyond the proximal tip 420 of theimplant 400 to aid in dissecting across or through the anulus 10proximate to the desired implantation site.

The implant guide 430 is releasable from the implant 400 following orduring implantation. This release may be coordinated with the release ofthe guide filaments 422 and 424. The implant guide 430 may further beable to slide along the guide filaments 422 and 424 while thesefilaments are secured to the implant 400.

Various embodiments of the barrier 12 or implant 400 can be secured totissues within the intervertebral disc 15 or surrounding vertebrae. Itcan be advantageous to secure the barrier means 12 in a limited numberof sites while still insuring that larger surfaces of the barrier 12 orimplant juxtapose the tissue to which the barrier 12 is secured. This isparticularly advantageous in forming a sealing engagement withsurrounding tissues.

FIGS. 53-57 illustrate barriers 12 having stiffening elements 300. Thebarrier 12 can incorporate stiffening elements 300 that run along alength of the implant required to be in sealing engagement. Thesestiffening elements 300 can be one of a variety of shapes including, butnot limited to, plates 302, rods 304, or coils. These elements arepreferably stiffer than the surrounding barrier 12 and can impart theirstiffness to the surrounding barrier. These stiffening elements 300 canbe located within an interior cavity formed by the barrier. They canfurther be imbedded in or secured to the barrier 12.

Each stiffening element can aid in securing segments of the barrier 12to surrounding tissues. The stiffening elements can have parts 307,including through-holes, notches, or other indentations for example, tofacilitate fixation of the stiffening element 300 to surrounding tissuesby any of a variety of fixation devices 306. These fixation devices 306can include screws, darts, dowels, or other suitable means capable ofholding the barrier 12 to surrounding tissue. The fixation devices 306can be connected either directly to the stiffening element 300 orindirectly using an intervening length of suture, cable, or otherfilament for example. The fixation device 306 can further be secured tothe barrier 12 near the stiffening element 300 without direct contactwith the stiffening element 300.

The fixation device 306 can be secured to or near the stiffening element300 at opposing ends of the length of the barrier 12 required to be insealing engagement with surrounding tissues. Alternatively, one or amultitude of fixation devices 306 can be secured to or near thestiffening element 300 at a readily accessible location that may not beat these ends. In any barrier 12 embodiment with an interior cavity 17and an opening 8 leading thereto, the fixation sites may be proximal tothe opening 8 to allow passage of the fixation device 306 and variousinstruments that may be required for their implantation.

FIGS. 53A and 53B illustrate one embodiment of a barrier 12incorporating the use of a stiffening element 300. The barrier 12 can bea plate and screw barrier 320. In this embodiment, the stiffeningelement 300 consists of two fixation plates, superior 310 and inferior312, an example of which is illustrated in FIGS. 54A and 54B with twoparts 308 passing through each plate. The parts 308 are located proximalto an opening 8 leading into an interior cavity 17 of the barrier 12.These parts 8 allow passage of a fixation device 306 such as a bonescrew. These screws can be used to secure the barrier means 12 to asuperior 50 and inferior 50′ vertebra. As the screws are tightenedagainst the vertebral endplate, the fixation plates 310, 312 compressthe intervening sealing means against the endplate along the superiorand inferior surfaces of the barrier 12. This can aid in creating asealing engagement with the vertebral endplates and prevent egress ofmaterials from within the disc 15. As illustrated in FIGS. 53A and 53B,only the superior screws have been placed in the superior plate 310,creating a sealing engagement with the superior vertebra.

FIGS. 55A and 55B illustrate another embodiment of a barrier 12 havingstiffening elements 300. The barrier 12 can be an anchor and rod barrier322. In this embodiment, the stiffening elements 300 consist of twofixation rods 304, an example of which is shown in FIGS. 56A and 56B,imbedded within the barrier 12. The rods 304 can include a superior rod314 and an inferior rod 316. Sutures 318 can be passed around these rods314 and 316 and through the barrier means 10. These sutures 318 can inturn, be secured to a bone anchor or other suitable fixation device 306to draw the barrier 12 into sealing engagement with the superior andinferior vertebral endplates in a manner similar to that describedabove. The opening 8 and interior cavity 17 of the barrier 12 are notrequired elements of the barrier 12.

FIG. 57 illustrates the anchor and rod barrier 322, described above,with fixation devices 306 placed at opposing ends of each fixation rod316 and 318. The suture 18 on the left side of the superior rod 318 hasyet to be tied.

Various methods may be employed to decrease the forces necessary tomaneuver the barrier 12 into a position along or within the lamellae ofthe anulus fibrosis 10. FIGS. 58A, 58B, 59A and 59B depict two preferredmethods of clearing a path for the barrier 12.

FIGS. 58A and 58B depict one such method and an associated dissectordevice 454. In these figures, the assumed desired position of theimplant is along the posterior anulus 452. In order to clear a path forthe implant, a hairpin dissector 454 can be passed along the intendedimplantation site of the implant. The hairpin dissector 454 can have ahairpin dissector component 460 having a free end 458. The dissector canalso have an advancer 464 to position the dissector component 460 withinthe disc 15. The dissector 454 can be inserted through cannula 456 intoan opening 462 in the anulus 10 along an access path directed anteriorlyor anterior-medially. Once a free-end 458 of the dissector component 460is within the disc 15, the free-end 458 moves slightly causing thehairpin to open, such that the dissector component 460 resists returninginto the cannula 456. This opening 462 can be caused by pre-forming thedissector to the opened state. The hairpin dissector component 460 canthen be pulled posteriorly, causing the dissector component 460 to open,further driving the free-end 458 along the posterior anulus 458. Thismotion clears a path for the insertion of any of the implants disclosedin the present invention. The body of dissector component 460 ispreferably formed from an elongated sheet of metal. Suitable metalsinclude various spring steels or nickel titanium alloys. It canalternatively be formed from wires or rods.

FIGS. 59A and 59B depict another method and associated dissector device466 suitable for clearing a path for implant insertion. The dissectordevice 466 is shown in cross section and consists of a dissectorcomponent 468, an outer cannula 470 and an advancer or inner push rod472. A curved passage or slot 474 is formed into an intradiscal tip 476of outer cannula 470. This passage or slot 474 acts to deflect the tipof dissector component 468 in a path that is roughly parallel to thelamellae of the anulus fibrosis 10 as the dissector component 468 isadvanced into the disc 15 by the advancer. The dissector component 468is preferably formed from a superelastic nickel titanium alloy, but canbe constructed of any material with suitable rigidity and straincharacteristics to allow such deflection without significant plasticdeformation. The dissector component 468 can be formed from an elongatedsheet, rods, wires or the like. It can be used to dissect between theanulus 10 and nucleus 20, or to dissect between layers of the anulus 10.

FIGS. 60A-C depict an alternate dissector component 480 of FIGS. 59A and59B. Only the intradiscal tip 476 of device 460 and regions proximalthereto are shown in these figures. A push-rod 472 similar to that shownin FIG. 59A can be employed to advance dissector 480 into the disc 15.Dissector 480 can include an elongated sheet 482 with superiorly andinferiorly extending blades (or “wings”) 484 and 486, respectively. Thissheet 482 is preferably formed from a metal with a large elastic strainrange such as spring steel or nickel titanium alloy. The sheet 482 canhave a proximal end 488 and a distal end 490. The distal end 490 canhave a flat portion which can be flexible. A step portion 494 can belocated between the distal end 490 and the proximal end 488. Theproximal end 488 can have a curved shape. The proximal end can alsoinclude blades 484 and 486.

In the undeployed state depicted in FIGS. 60A and 60B, wings 484 and 486are collapsed within outer cannula 470 while elongated sheet 482 iscaptured within deflecting passage or slot 474. As the dissectorcomponent 480 is advanced into a disc 15, passage or slot 478 directsthe dissector component 480 in a direction roughly parallel to theposterior anulus (90 degrees to the central axis of sleeve 470 in thiscase) in a manner similar to that described for the embodiment in FIGS.59A and 59B. Wings 484 and 486 open as they exit the end of sleeve 470and expand toward the vertebral endplates. Further advancement ofdissector component 480 allows the expanded wings 484 and 486 to dissectthrough any connections of nucleus 20 or anulus 10 to the endplates thatmay present an obstruction to subsequent passage of the implants of thepresent invention. When used to aid in the insertion of a barrier, thedimensions of dissector component 480 should approximate those of thebarrier such that the minimal amount of tissue is disturbed whilereducing the forces necessary to position the barrier in the desiredlocation.

FIGS. 61A-61D illustrate a method of implanting a disc implant. A discimplant 552 is inserted into a delivery device 550. The delivery device550 has a proximal end 556 and a distal end 558. The distal end 558 ofthe delivery device 550 is inserted into an annulotomy illustrated inFIG. 61A. The annulotomy is preferably located at a site within theanulus 10 that is proximate to a desired, final implant 552 location.The implant 400 is then deployed by being inserted into the disc 15through the distal end 558 of the delivery device 550. Preferably theimplant is forced away from the final implant location, as shown in FIG.61B. An implant guide 560 can be used to position the implant 400.Before, during or after deployment of the implant 400, an augmentationmaterial 7 can be injected into the disc 15. Injection of augmentationafter deployment is illustrated in FIG. 61C. The augmentation material 7can include a hydrogel or collagen, for example. In one embodiment, thedelivery device 550 is removed from the disc 15 and a separate tube isinserted into the annulotomy to inject the flowable augmentationmaterial 7. Alternately, the distal end 558 of the delivery device 550can remain within the annulotomy and the fluid augmentation material 554injected through the delivery device 550. Next, the delivery device 550is removed from the annulotomy and the intradiscal implant 400 ispositioned over the annulotomy in the final implant location, as shownin FIG. 61D. The implant 400 can be positioned using control filamentsdescribed above.

Certain embodiments, as shown in FIGS. 62-66, depict anulus and nuclearaugmentation devices which are capable of working in concert to restorethe natural biomechanics of the disc. A disc environment with adegenerated or lesioned anulus cannot generally support the loadtransmission from either the native nucleus or from prostheticaugmentation. In many cases, nuclear augmentation materials 7 bulgethrough the anulus defects, extrude from the disc, or applypathologically high load to damaged regions of the anulus. Accordingly,in one aspect of the current invention, damaged areas of the anulus areprotected by shunting the load from the nucleus 20 or augmentationmaterials 7 to healthier portions of the anulus 10 or endplates. Withthe barrier-type anulus augmentation 12 in place, as embodied in variousaspects of the present invention, nuclear augmentation materials 7 ordevices can conform to healthy regions of the anulus 10 while thebarrier 12 shields weaker regions of the anulus 10. Indeed, the anulusaugmentation devices 12 of several embodiments of the present inventionare particularly advantageous because they enable the use of certainnuclear augmentation materials and devices 7 that may otherwise beundesirable in a disc with an injured anulus.

FIG. 62 is a cross-sectional transverse view of an anulus barrier device12 implanted within a disc 15 along the inner surface of a lamella 16.Implanted conformable nuclear augmentation 7 is also shown in contactwith the barrier 12. The barrier device 12 is juxtapositioned to theinnermost lamella of the anulus. Conformable nuclear augmentationmaterial 7 is inserted into the cavity which is closed by the barrier12, in an amount sufficient to fill the disc space in an unloaded supineposition. As shown, in one embodiment, fluid nuclear augmentation 554,such as hyaluronic acid, is used.

Fluid nuclear augmentation 554 is particularly well-suited for use invarious aspects of the current invention because it can be deliveredwith minimal invasiveness and because it is able to flow into and fillminute voids of the intervertebral disc space. Fluid nuclearaugmentation 554 is also uniquely suited for maintaining a pressurizedenvironment that evenly transfers the force exerted by the endplates tothe anulus augmentation device and/or the anulus. However, fluid nuclearaugmentation materials 554 used alone may perform poorly in discs 15with a degenerated anulus because the material can flow back out throughanulus defects 8 and pose a risk to surrounding structures. Thislimitation is overcome by several embodiments of the current inventionbecause the barrier 12 shunts the pressure caused by the fluidaugmentation 554 away from the damaged anulus region 8 and towardhealthier regions, thus restoring function to the disc 15 and reducingrisk of the extrusion of nuclear augmentation materials 7 and fluidaugmentation material 554.

Exemplary fluid nuclear augmentation materials 554 include, but are notlimited to, various pharmaceuticals (steroids, antibiotics, tissuenecrosis factor alpha or its antagonists, analgesics); growth factors,genes or gene vectors in solution; biologic materials (hyaluronic acid,non-crosslinked collagen, fibrin, liquid fat or oils); syntheticpolymers (polyethylene glycol, liquid silicones, synthetic oils); andsaline. One skilled in the art will understand that any one of thesematerials may be used alone or that a combination of two or more ofthese materials may be used together to form the nuclear augmentationmaterial.

Any of a variety of additional additives such as thickening agents,carriers, polymerization initiators or inhibitors may also be included,depending upon the desired infusion and long-term performancecharacteristics. In general, “fluid” is used herein to include anymaterial which is sufficiently flowable at least during the infusionprocess, to be infused through an infusion lumen in the delivery deviceinto the disc space. The augmentation material 554 may remain “fluid”after the infusion step, or may polymerize, cure, or otherwise harden toa less flowable or nonflowable state.

Additional additives and components of the nucleus augmentation materialare recited below. In general, the nature of the material 554 may remainconstant during the deployment and post-deployment stages or may change,from a first infusion state to a second, subsequent implanted state. Forexample, any of a variety of materials may desirably be infused using acarrier such as a solvent or fluid medium with a dispersion therein. Thesolvent or liquid carrier may be absorbed by the body or otherwisedissipate from the disc space post-implantation, leaving the nucleusaugmentation material 554 behind. For example, any of a variety of thepowders identified below may be carried using a fluid carrier. Inaddition, hydrogels or other materials may be implanted or deployedwhile in solution, with the solvent dissipating post-deployment to leavethe hydrogel or other media behind. In this type of application, thedisc space may be filled under higher than ultimately desired pressure,taking into account the absorption of a carrier volume. Additionalspecific materials and considerations are disclosed in greater detailbelow.

FIG. 63 is a cross-sectional transverse view of anulus barrier device 12implanted within a disc 15 along an inner surface of a lamella 16.Implanted nuclear augmentation 7 comprised of a hydrophilic flexiblesolid is also shown. Nuclear augmentation materials include, but are notlimited to, liquids, gels, solids, gases or combinations thereof.Nuclear augmentation devices 7 may be formed from one or more materials,which are present in one or more phases. FIG. 63 shows a cylindricalflexible solid form of nuclear augmentation 7. Preferably, this flexiblesolid is composed of a hydrogel, including, but not limited to,acrylonitrile, acrylic acid, polyacrylimide, acrylimide, acrylimidine,polyacrylonitrile, polyvinylalcohol, and the like.

FIG. 63 depicts nuclear augmentation 7 using a solid or gel composition.If required, these materials can be designed to be secured tosurrounding tissues by mechanical means, such as glues, screws, andanchors, or by biological means, such as glues and in growth. Solid butdeformable augmentation materials 7 may also be designed to resist axialcompression by the endplates rather than flowing circumferentiallyoutward toward the anulus. In this way, less force is directed at theanulus 10. Solid nuclear augmentation 7 can also be sized substantiallylarger than the annulotomy 416 or defect 8 to decrease the risk ofextrusion. The use of solid materials or devices 7 alone is subject tocertain limitations. The delivery of solid materials 7 may require alarge access hole 417 in the anulus 10, thereby decreasing the integrityof the disc 15 and creating a significant risk for extrusion of eitherthe augmentation material 7 or of natural nucleus 20 remaining withinthe disc 15. Solid materials or devices 7 can also overload theendplates causing endplate subsidence or apply point loads to the anulus10 from corners or edges that may cause pain or further deterioration ofthe anulus 10. Several embodiments of the present invention overcome thelimitations of solid materials and are particularly well-suited for usewith liquid augmentation materials 7. The barrier device 12 of variousembodiments of this invention effectively closes the access hole 417 andcan be adapted to partially encapsulate the augmented nucleus, thusmitigating the risks posed by solid materials.

Solid or gel nuclear augmentation materials 7 used in variousembodiments of the current invention include single piece or multiplepieces. The solid materials 7 may be cube-like, spheroid, disc-like,ellipsoid, rhombohedral, cylindrical, or amorphous in shape. Thesematerials 7 may be in woven or non-woven form. Other forms of solidsincluding minute particles or even powder can be considered when used incombination with the barrier device. Candidate materials 7 include, butare not limited to: metals, such as titanium, stainless steels, nitinol,cobalt chrome; resorbable or non-resorbing synthetic polymers, such aspolyurethane, polyester, PEEK, PET, FEP, PTFE, ePTFE, Teflon, PMMA,nylon, carbon fiber, Delrin, polyvinyl alcohol gels, polyglycolic acid,polyethylene glycol; silicon gel or rubber, vulcanized rubber or otherelastomer; gas filled vesicles, biologic materials such as morselized orblock bone, hydroxy apetite, cross-linked collagen, muscle tissue, fat,cellulose, keratin, cartilage, protein polymers, transplanted orbioengineered nucleus pulposus or anulus fibrosus; or variouspharmacologically active agents in solid form. The solid or gelaugmentation materials 7 may be rigid, wholly or partially flexible,elastic or viscoelastic in nature. The augmentation device or material 7may be hydrophilic or hydrophobic. Hydrophilic materials, mimicking thephysiology of the nucleus, may be delivered into the disc in a hydratedor dehydrated state. Biologic materials may be autologous, allograft,zenograft, or bioengineered.

In various embodiments of the present invention, the solid or gelnuclear augmentation material 7, as depicted in FIG. 63, are impregnatedor coated with various compounds. Preferably, a biologically activecompound is used. In one embodiment, one or more drug carriers are usedto impregnate or coat the nuclear augmentation material 7. Geneticvectors, naked genes or other therapeutic agents to renew growth, reducepain, aid healing, and reduce infection may be delivered in this manner.Tissue in-growth, either fibrous (from the anulus) or bony (from theendplates), within or around the augmentation material can be eitherencouraged or discouraged depending on the augmentation used. Tissuein-growth may be beneficial for fixation and can be encouraged viaporosity or surface chemistry. Surface in-growth or other methods offixation of the augmentation material 7 can be encouraged on a singlesurface or aspect so as to not interfere with the normal range of motionof the spinal unit. In this way, the material is stabilized and safelycontained within the anulus 10 without resulting in complete fixationwhich might cause fusion and prohibit disc function.

FIG. 64 is a cross-sectional transverse view of anulus barrier device 12implanted within a disc 15 along an inner surface of a lamella 16.Several types of implanted nuclear augmentation 7, including a solidcube, a composite cylindrical solid 555, and a free flowing liquid 554are shown. The use of multiple types of nuclear augmentation with thebarrier 12 is depicted in FIG. 64. The barrier device 12 is shown incombination with fluid nuclear augmentation 554, solid nuclearaugmentation 7, in the form of a cube, and a cross-linked collagensponge composite 555 soaked in a growth factor. In several embodimentsof the present invention, a multiphase augmentation system, as shown inFIG. 64, is used. A combination of solids and liquids is used in apreferred embodiment. Nuclear augmentation 7 comprising solids andliquids 554 can be designed to create primary and secondary levels offlexibility within an intervertebral disc space. In use, the spine willflex easily at first as the intervertebral disc pressure increases andthe liquids flows radially, loading the anulus. Then, as the disc heightdecreases and the endplates begin to contact the solid or gelatinousaugmentation material, flexibility will decrease. This combination canalso prevent damage to the anulus 10 under excessive loading as thesolid augmentation 7 can be designed to resist further compression suchthat the fluid pressure on the anulus is limited. In a preferredembodiment, use of multiphase augmentation allows for the combination offluid medications or biologically active substances with solid orgelatinous carriers. One example of such a preferable combination is across-linked collagen sponge 555 soaked in a growth factor orcombination of growth factors in liquid suspension.

In one embodiment, the nuclear augmentation material or device 7, 554constructed therefrom is phase changing, e.g., from liquid to solid,solid to liquid, or liquid to gel. In situ polymerizing nuclearaugmentation materials are well-known in the art and are described inU.S. Pat. No. 6,187,048, herein incorporated by reference. Phasechanging augmentation preferably changes from a liquid to a solid orgel. Such materials may change phases in response to contact with air,increases or decreases in temperature, contact with biologic liquids orby the mixture of separate reactive constituents. These materials areadvantageous because they can be delivered through a small hole in theanulus or down a tube or cannula placed percutaneously into the disc.Once the materials have solidified or gelled, they can exhibit thepreviously described advantages of a solid augmentation material. In apreferred embodiment, the barrier device is used to seal and pressurizea phase changing material to aid in its delivery by forcing it into thevoids of the disc space while minimizing the risk of extrusion of thematerial while it is a fluid. In this situation, the barrier or anulusaugmentation device 12 may be permanently implanted or used onlytemporarily until the desired phase change has occurred.

In another embodiment, an anulus augmentation device 12 that exploitsthe characteristics of nucleus augmentation devices or materials toimprove its own performance is provided. Augmenting the nucleus 20pressurizes the intervertebral disc environment which can serve to fixor stabilize an anulus repair device in place. The nucleus 20 can bepressurized by inserting into the disc 15 an adequate amount ofaugmentation material 7, 554. In use, the pressurized disc tissue andaugmentation material 7, 554 applies force on the inwardly facingsurface of the anulus augmentation device 12. This pressure may beexploited by the design of the anulus prosthesis or barrier 12 toprevent it from dislodging or moving from its intended position. Oneexemplary method is to design the inwardly facing surface of the anulusprosthesis 12 to expand upon the application of pressure. As the anulusprosthesis 12 expands, it becomes less likely to be expelled from thedisc. The prosthesis 12 may be formed with a concavity facing inward topromote such expansion.

In several embodiments, the anulus augmentation device 12 itselffunctions as nuclear augmentation 7. In a preferred embodiment, thebarrier 12 frame is encapsulated in ePTFE. This construct typicallydisplaces a volume of 0.6 cubic centimeters, although thicker coatingsof ePTFE or like materials may be used to increase this volume to 3cubic centimeters. Also, the anulus augmentation device may be designedwith differentially thickened regions along its area.

FIG. 65 depicts a sagittal cross-sectional view of the barrier deviceconnected to an inflatable nuclear augmentation device 455. The barrierdevice 12 is shown connected via hollow delivery and support tube 425 toan nuclear augmentation sack 455 suitable for containing fluid material554. The tube 425 has a delivery port or valve 450 that extends throughthe barrier device and can be accessed from the access hole 417 afterthe barrier device 12 and augmentation sack 455 has been delivered. Thisnuclear and anulus augmentation combination is particularly advantageousbecause of the ease of deliverability, since the sack 455 and thebarrier 12 are readily compressed. The connection of the barrier 12 andthe augmentation sack 455 also serves to stabilize the combination andprevent its extrusion from the disc 15. The nuclear augmentation 7 maybe secured to the anulus augmentation prosthesis 12 to create aresistance to migration of the overall construct. Such attachment mayalso be performed to improve or direct the transfer of load from thenuclear prosthesis 7 through the anulus prosthesis 12 to the disctissues. The barrier 12 and augmentation 7 can be attached prior to,during, or after delivery of the barrier 12 into the disc 15. They maybe secured to each other by an adhesive or by a flexible filament suchas suture. Alternatively, the barrier 12 may have a surface facing theaugmentation material 7 that bonds to the augmentation material 7 thougha chemical reaction. This surface may additionally allow for amechanical linkage to a surface of the augmentation material 7. Thislinkage could be achieved through a porous attachment surface of thebarrier 12 that allows the inflow of a fluid augmentation material 7that hardens or gels after implantation.

Alternatively, the anulus augmentation device 12 and nuclearaugmentation material 7 may be fabricated as a single device with abarrier 12 region and a nuclear augmentation region 7. As an example,the barrier 12 may form at least a portion of the surface of anaugmentation sack 455 or balloon. The sack 455 may be filled withsuitable augmentation materials 7 once the barrier has been positionedalong a weakened inner surface of the anulus 10.

The sequence of inserting the barrier 12 and nuclear augmentation 7 inthe disc can be varied according to the nuclear augmentation 7 used orrequirements of the surgical procedure. For example, the nuclearaugmentation 7 can be inserted first and then sealed in place by thebarrier device 12. Alternatively, the disc 15 can be partially filled,then sealed with the barrier device 12, and then supplied withadditional material 7. In a preferred embodiment, the barrier device 12is inserted into the disc 15 followed by the addition of nuclearaugmentation material 7 through or around the barrier 12. This allowsfor active pressurization. A disc 15 with a severely degenerated anuluscan also be effectively treated in this manner.

In an alternative embodiment, the nuclear augmentation material 7 isdelivered through a cannula inserted through an access hole 417 in thedisc 15 formed pathologically, e.g. an anular defect 8, oriatrogenically, e.g. an anuulotomy 416 that is distinct from the accesshole 417 that was used to implant the barrier 12. Also, the same ordifferent surgical approach including transpsoas, presacral,transsacral, tranpedicular, translaminar, or anteriorly through theabdomen, may be used. Access hole 417 can be located anywhere along theanulus surface or even through the vertebral endplates.

In alternative embodiments, the anulus augmentation device 12 includesfeatures that facilitate the introduction of augmentation materials 554following placement. The augmentation delivery cannula may simply beforcibly driven into an access hole 417 proximal to the barrier 12 at aslight angle so that the edge of the barrier 12 deforms and allowspassage into the disc space. Alternatively, a small, flexible or rigidcurved delivery needle or tube may be inserted through an access hole417 over (in the direction of the superior endplate) or under (in thedirection of the inferior endplate) the barrier 12 or around an edge ofthe barrier 12 contiguous with the anulus 15.

In several embodiments, ports or valves are installed in the barrier 12device that permit the flow of augmentation material into, but not outof, the disc space. One-way valves 450 or even flaps of material heldshut by the intervertebral pressure may be used. A collapsible tubularvalve may be fashioned along a length of the barrier. In one embodiment,multiple valves or ports 450 are present along the device 12 tofacilitate alignment with the access hole 417 and delivery ofaugmentation material. Flow channels within or on the barrier 12 todirect the delivery of the material 554 (e.g. to the ends of thebarrier) can be machined, formed into or attached to the barrier 12along its length. Alternatively, small delivery apertures (e.g. causedby a needle) can be sealed with a small amount of adhesive or suturedshut.

FIG. 66 is sagittal cross-sectional view of a functional spine unitcontaining the barrier device unit 12 connected to a wedge-shapednuclear augmentation 7 device. FIG. 66 illustrates that the geometry ofthe nuclear augmentation 7 can be adapted to improve the function of thebarrier. By presenting nuclear augmentation 7 with a wedge-shaped orhemicircular profile towards the interior of the intervertebral discspace, and attaching it in the middle of the barrier device 12 betweenthe flexible finger-like edges of the barrier device, the force exertedby the pressurized environment is focused in the direction of the edgesof the barrier device sealing them against the endplates. Accordingly,this wedge-shaped feature improves the function of the device 12. Oneskilled in the art will understand that the nuclear augmentationmaterial 7 may also be designed with various features that improve itsinteraction with the barrier, such as exhibiting different flexibilityor viscosity throughout its volume. For example, in certainapplications, it may be preferable for the augmentation 7 to be eitherstiff at the interface with the barrier 12 and supple towards the centerof the disc, or vice versa. The augmentation 7 can also serve torotationally stabilize the barrier 12. In this embodiment, theaugmentation is coupled to the inward facing surface of the barrier andextends outward and medially into the disc forming a lever arm andappearing as “T-shaped” unit. The augmentation device 7 of thisembodiment can extend from the middle of the disc 15 to the oppositewall of the anulus.

In one embodiment, the anulus augmentation device comprises a mesh. FIG.67 shows one example of a meshed anulus augmentation device. In oneembodiment, a repair mesh that is resilient is provided. In someembodiments, the mesh is particularly advantageous because it canwithstand millions of motion cycles within the disc environment, and isresistant to fatigue. In several embodiments, fatigue resistance isaccomplished by material properties, structural design, or a combinationthereof. For a given material, a fatigue resistant structure can bedesigned to distribute the strain of deformation as evenly as possibleover as much material as possible so as to minimize stressconcentrations that could initiate fatigue cracks. For example, a coiledspring may deform millions of times without failure or cracking becausethe strain is distributed evenly over a length of metal. For an anulusrepair mesh, the same effect maybe achieved by means such as, but notlimited to, providing more material for a given deformation site byhaving mesh members curved throughout their lengths, alternating meshcurves in a sine-wave or zigzag pattern to provide more material anddistributed strains, or having longer non linear members such that agiven deformation results in less material strain, or pre-shaping theimplant to minimize strain at the implantation site. The curvilinear,nonlinear, coiled, or angled members can be interconnected, woven,networked, or emanate from or be attached to rails or members to form aframework or define a mesh or barrier.

In one embodiment, a mesh can be used in a variety of locations in andaround the intervertebral disc. It can be placed on an external surfaceof the anulus, along an endplate, within the anulus, between the anulusand nucleus, within the nucleus, or within both the anulus and nucleus.The mesh can be held in place via counteracting forces of the mesh as itflexes from its unstressed shape to stressed shape or friction with disctissue, between disc and vertebral body tissue or between discaugmentation material or another implant and disc tissue. The mesh canalso have a porosity or macrotexture including ridges, spikes or spiralsto increase bioincorporation and fixation. Fixation devices, includingbut not limited to, sutures, glue, screws, and staples can be used topermanently fix the mesh in place.

In one embodiment, the anulus augmentation device is a barriercomprising a membrane and a frame. In some embodiments, the frame is themesh. In other embodiment, the mesh is coated with the membrane. Inanother embodiment, the anulus augmentation device comprises only aframe.

In one embodiment, the mesh or frame region of the implant canpreferably be formed from a relatively thin sheet of material. Thematerial may be a polymer (including in-situ polymerizing), metal, orgel. However, as discuss infra, the superelastic properties of nickeltitanium alloy (NITINOL) makes this metal particularly advantageous inthis application. Other materials suitable for this application includeone or more of the following: nylon, polyvinyl alcohol, polyethylene,polyurethane, polypropylene, polycaprolactone, polyacrylate,ethylene-vinyl acetates, polystyrene, polyvinyl oxide, polyvinylfluoride, polyvinyl imidazole, chlorosulphonated polyolefins,polyethylene oxide, polytetrafluoroethylene and nylon, and copolymersand combinations thereof, polycarbonate, Kevlar™, acetal, cobalt chrome,carbon, graphite, metal matrix composites, stainless steel and othermetals, alloys and composites. Some materials may be coated to achievebiocompatibility. These materials can also be used for frames or supportmember that do not comprise meshes.

In some embodiments, the mesh or frame designs may have sharp edges orhave gaps that may allow for tissue transfer outside of the disc. In oneembodiment, a membrane may be secured to one or more sides or portionsof the mesh or frame in order to resist transfer of particles across itsperiphery and outside of the disc or to shield the body from the mesh'ssharp edges. Also, a membrane can prevent the flow of a material boundedby the anulus fibrosis of the intervertebral disc through a defect inthe anulus fibrosis if the device is positioned across the defect.

In a preferred embodiment, the size of the mesh device is dictated bythe particular region of the functional spinal unit sought to betreated. For example, In one embodiment, a mesh intended for coveragethe interior surface of the posterior lateral anulus can be about 2 cmto about 4 cm in length and about 2 mm to about 15 mm in height.Likewise, the mesh can be sized to cover the entire exterior or interiorsurface of a disc. Also, if a defect or weakened segment of the disc ispre-opertively identified, the size of the mesh can be selected toadequately span it in more than one direction. In one embodiment, themesh is sized such that it spans all directions by at least about 2 mm.The overlap provided by the about 2 mm or more mesh, in someembodiments, provides mechanical means by which the mesh resistsextrusion through a defect. Where a case dictates that a device is notavailable for full coverage of a portion of the anulus, the surgeon canselect a mesh, barrier, or patch that is sized such that even if thebarrier shifts along an axis in either direction, the selected widthensures that there remains about 2 mm or more of the device beyond theedge of the defect in all positions along that portion of the anulus. Inthis way a surgeon can determine a minimum implant size that will stillbe efficacious.

In one embodiment, the anulus augmentation device, such as a mesh or amembrane/frame combination, has a thickness in a range between about0.025 mm to about 3 mm. Nucleus pulposus particles have been measured ataround 0.8 mm². Accordingly, in one embodiment, the anulus augmentationdevice, such as a mesh or a membrane/frame combination, has poresslightly smaller (e.g., about 0.05 mm² to about 0.75 mm²) and stillfunction as a means to prevent extrusion of nuclear material from thedisc. Alternatively, one of ordinary skill in the art can throughexperimentation determine the size of disc particles sought to becontained by the mesh and size the pores slightly smaller. Such a designaffords the fluid transfer of other smaller particles and especiallywater, blood, and other tissue fluids.

In several embodiments, the cross-section of the mesh can be flat,concave, convex or hinged (or flexibly connected) along at least aportion of one or more horizontal axes or vertical axes. One of skill inthe art will understand that other cross-sections can also be used inaccordance with several embodiments of the invention.

It has been determined that in procedures wherein only a limited amountof nucleus or anulus tissue is removed from a pathologic disc,approximately 0.2 to about 2.0 cc of tissue is typically removed.Accordingly, to replace this volume loss and contribute to thebiomechanical function of the spine, spinal implants can be designed toreplace this volume (about 0.2 to 2.0 cc) through selection of materialsand their dimensions. Accordingly, in one embodiment, an implant havinga volume of about 0.2 to about 2.0 cc is provided. The implant caninclude an anulus augmentation device, a nuclear augmentation device oran anulus augmentation/nuclear augmentation combination device.Preferably, a device having an overall volume of about 0.5 cc isprovided because this is the most typical volume removed. Also, greatervolumes may be used to further increase the volume of the disc in caseswhere disc height has decreased over time and the fragments have beenmetabolized (and thus do not require removal).

In one embodiment, an implant comprising a frame and a membrane isprovided. In other embodiments, the implant comprises only one or moremembranes. In one embodiment, the implant comprises only one or moreframes. The frame may be coated. The membrane (or coating) can becomprised of any suitably durable and flexible material includingpolymers, elastomers, hydrogels and gels such as polyvinyl alcohol,polyethylene, polyurethane, polypropylene, polycaprolactone,polyacrylate, ethylene-vinyl acetates, polystyrene, polyvinyl oxides,polyvinyl fluorides, polyvinyl imidazole, chlorosulphonated polyolefin,polyethylene oxide, polytetrafluoroethylene, a nylon, silicone, rubber,polylactide, polyglycolic acid, polylactide-co-glycolide,polycaprolactone, polycarbonate, polyamide, polyanhydride, polyaminoacid, polyortho ester, polyacetal, polycyanoacrylate, degradablepolyurethane, copolymers and derivatives and combinations thereof.Biological materials including keratin, albumin collagen, elastin,prolamines, engineered protein polymers, and derivatives andcombinations thereof, may also be used.

In one embodiment, at least a portion of the anulus augmentation device(e.g., the membrane, mesh, barrier, etc) can be impregnated with, coatedwith, or designed to carry and deliver diagnostic agents and/ortherapeutic agents. Diagnostic agents include, but are not limited to,radio-opaque materials suitable to permit imaging by MRI or X-ray.Therapeutic agents include, but are not limited to, steroids, geneticvectors, antibodies, antiseptics, growth factors such as somatomedins,insulin-like growth factors, fibroblast growth factors, bone morphogenicgrowth factors, endothelial growth factors, transforming growth factors,platelet derived growth factors, hepatocytic growth factors,keratinocyte growth factors, angiogenic factors, immune systemsuppressors, antibiotics, living cells such as fibroblasts,chondrocytes, chondroblasts, osteocytes, mesenchymal cells, epithelialcells, and endothelial cells, and cell-binding proteins and peptides. Inother embodiments, the nuclear augmentation device can be impregnated,coated, or designed to carry diagnostic and/or therapeutic agents.

In one embodiment, as shown in FIG. 67, a mesh having a series ofcurvilinear elements 602 is provided. In one embodiment, the curvilinearelements 602 are interconnected. One of skill in the art will understandthat the curvilinear elements 602 can exist independently of each other,or only be partially connected. The interconnections 602 can bedistributed to form one or more contiguous horizontal bands, rails,members, struts, or axes 604. FIG. 67 shows such a device with a centralhorizontal axis 604 and “S” shaped curvilinear elements 602. In oneembodiment, the “S” shaped elements 602 tend to distribute the stressgenerated under compression over a larger area. In one embodiment, onlyportions of the “S” move out of plane during loading providingstiffness. In some embodiments, the curvilinear elements areparticularly advantageous because they provide flexibility, resilienceand/or rigidity.

In some embodiments, the curvilinear elements 602 can be oriented about90 degrees (curving in the ventral/dorsal axis) such that the curvesappear in the overall horizontal cross-section of the implant. In otherembodiments, the curvilinear elements 602 are substantially flat. Thecurvilinear elements 602 can also be oriented at any angle (e.g., fromabout 1 degree to about 179 degrees) from the plane. The mesh 600 can bestraight, convex or concave in cross-section. FIGS. 68A-G show theprofile of a mesh with various curvilinear elements. FIGS. 68D-G showtop cross-sectional views of the mesh being elongated “U” shaped, “C”shaped, curvilinear shaped (like a typical posterior anulus interiorsurface), and “D” shaped to extend along and cover the entire inneranulus surface, or portions thereof.

FIG. 69 shows yet another embodiment of a mesh 600 implanted in anintervertebral disc. Here, the curvilinear elements 602 comprisesprings, coils, or telescopic members that are adapted to compressaxially (like pneumatic pistons or coil springs) under loading ratherthan bending and conforming to a tissue surface, e.g. the inner surfaceof the anulus. One advantage of a spring or coil-type mesh is that themesh can be fairly rigid and resistant to lateral or transverse forcebut is flexible enough to span around the curvatures of the disc whilemaintaining contact with the endplates under compression and expansion.Like other curvilinear elements, the springs or coils can beinterconnected, linked in a loose or hinge-like arrangement, attached toa horizontal band or axis, attached to a membrane, or encapsulatedwithin a membrane.

In one embodiment, the mesh may also be configured (e.g., from wire orstock) in a pattern comprising a series of repeating curved peaks andvalleys oriented in a lateral manner. Two or more curved wires may besuperimposed out of phase such that one peak is inferior to the adjacentwires valley. The two wires can be independent, contiguous and formedfrom a single wire, connected at one or more points, attached to amembrane, or encapsulated within a membrane. FIG. 70 shows a wire-typeanulus augmentation device.

As discussed above, an annulus augmentation device can comprise, forexample, a frame, a membrane or a frame/membrane combination. FIG. 70shows just the frame, which can be, for example, a wire or mesh-likedevice. FIGS. 71A-E show a mesh that has been encapsulated by a membraneor cover to produce an encapsulated mesh 606. FIG. 71C shows a top viewcross-section wherein the mesh is elongated U shaped and 71D through 71Fshow various side view cross-sections wherein the mesh is straight orpossesses varying degrees of concavity. As with other barriers disclosedherein, the membrane or encapsulation material may be of substantialthickness or may be substantially thin. Indeed, the encapsulationmaterial may simply be a coating.

In another embodiment, as shown in FIGS. 72A-B, a mesh 600 having adouble-wishbone frame with or without membrane cover is provided. Insome embodiments, this design is particularly advantageous because itreduces the compression and stress experienced by the implant underflexion, extension, and lateral bending. FIG. 72A shows the framewithout a membrane situated along a posterior portion of the disc. Theimplant (e.g., the frame) can also be placed on the outside of theanulus, within the anulus, between the nucleus and anulus or within thenucleus. Also shown is a defect 16 in the anulus 10 and placement of theframe 600 across the defect and spanning beyond it in more than a singledirection. FIG. 72B shows the mesh in a perspective view outside of thedisc. The frame (e.g., mesh) can be flat or an elongated “U” shapedcorresponding to the inner surface of the posterior anulus. In oneembodiment, the frame can be a single continuous band or wire formingtwo ends, a first end and a second end. In one embodiment, each endfunctions as a living hinge and forms an apex which may be in the formof a curve, a bend, or series of bends such that the wire is generallyredirected in the opposite direction. Accordingly, if a load is appliedalong the vertical axis at the midpoint of the frame, e.g., the midpointof the top and bottom (superior, inferior) rail, each corner or apex isloaded equally and the wire rails act as levers.

In one embodiment, the mesh 600 can be implanted such that the midpointof the mesh frame 600 is in the posterior of the disc and the endsreside medially or even in the anterior portion of the disc. In this waythe portion of the mesh 600 that undergoes the greatest compression isfurthest away from each end. Accordingly, a relatively large range ofmotion can be traversed by the middle of the device but this will onlytranslate to limited motion at each end or living hinge, thus reducingstress and fatigue. Also, by placing each end (which has a relativelysmall profile) at opposing sides at the midline of the disc (the centerof rotation) it is subjected to almost no direct loading under lateralbending, flexion, extension, or compression by the endplates.

FIGS. 73A-C shows other embodiments for the end or natural hinge portionof the frame (e.g., mesh 600), including a loop formation.

FIGS. 74A-C show some embodiments of the central band or strut 604.FIGS. 74A-B show a central reinforcement band 604 disposed between theends or apexes of the frame (e.g., mesh). As shown in FIG. 74B, thecentral band 604 can be positioned between the top rail (or wire) 603and bottom rail (or wire) 605. As shown in FIG. 74C, the central band604 can be elongated to form a concave cross-section between the top andbottom rail or wire.

In several embodiments of the invention, an implant (e.g., an anulusaugmentation device, such as a mesh) can exhibit different mechanicalproperties along various axes. For example, an implant can exhibitrigidity along a first axis and flexibility (or less rigidity) along asecond axis transverse or perpendicular to the first. Such an implantmight find particular utility along the wall of an anulus between twoadjacent vertebrae because such an environment will subject the implantto vertical compression (e.g., along the superior/inferior axis) yetwill not compress the implant laterally. As such, the implant can retainits rigidity along its horizontal axis. Rigidity along the horizontalaxis of anulus augmentation device is especially useful in someembodiments if the implant is placed in front of a weakened or defectivesurface of the anulus because a point load will like form at that regionwhen the disc is compressed under loading and could cause the implant tobend and extrude. Accordingly, an implant having a certain degree ofrigidity along its lateral axis resists such bending and extrusion.Moreover, because of the less rigid and more flexible behavior of theimplant along its vertical axis loads caused flexion and extension ofthe spine will allow the implant to flex naturally with the spine andnot injure the endplates.

In some embodiments, to achieve the differences in mechanicalproperties, any number of construction, material selection orfabrication techniques known in the art can be used. For example, theimplant may be made thicker or thinner at points along a particular axisor voids or patterns may be cut into the material. Also, a compositeimplant having different material sandwiched together can also be used.Struts, members, rails and the like may be added to, secured to, orintegral to the implant to provide stiffness and rigidity. Further, suchstiffening elements can be added during the implantation procedure.

In one embodiment, the implant can also be corrugated along an axis orotherwise be provided with bents or curves to provide stiffness. Agentle curve or “C” shaped cross-section that could also conform orcorrespond to the inner curved surface of an anulus is also preferablefor making a seal with the anulus and for resisting bending along theimplant horizontal axis e.g., the curve would resist flattening out,flexing or bending laterally. Also, in some embodiments the implant canbe oversized such that it remains in compression along one or more ofits axes in its implanted state such that even under flexion andextension of the spine the corrugations or curved sections never flattenout and thus retain rigidity (or less flexibility) along an axisperpendicular to the curves.

One of skill in the art will understand that, in several embodiments,the implant (e.g., an anulus augmentation device, such as a mesh) can bemore or less rigid or flexible, according to the preference of thepractitioner or disc environment. The degree of desired rigidity andflexibility along each axis can be determined based on factors such asdefect size, intervertebral pressure, implant deliverability, desireddegree of compression and disc height.

According to one embodiment of the invention, an implant has a “C”cross-section, a central rail and top and bottom rails, and curvilinearelements connect the rails. The frame or mesh can be comprised of any ofthe suitable materials discussed herein, (e.g. nickel titanium) and canalso be coated, covered, bonded, or coupled to a cover or membrane. Inone embodiment, the implant is more rigid along its lateral axis becauseof its “C” cross-section or the rails and less rigid along its verticalaxis because of the void caused by the pattern and lack of corrugationsor stiffening elements.

Though some embodiments of the invention disclose a mesh frame, patch,plate, biocompatible support member or barrier adapted to extend alongthe inner circumference of an anulus fibrosus, other embodimentscontemplate partial coverage of the anulus or tissue surface. For someembodiments that that cover less than the entire inner surface of theanulus or that are not fully anchored in place, and are susceptible tomigration, one or more projections extending outward from, or off-angleto the implant can be configured to resist migration or movement of theimplant within the disc under cyclical loading and movement of thespine. One advantage of such embodiments is that they can reduce orprevent migration. Undesired migration may render the implantineffective or cause it to pathologically interfere with adjacent tissueincluding the anulus, nucleus, endplates and spinal cord.

According to one embodiment, an implant can be stabilized within anintervertebral disc by providing a support member or patch with anoff-angle projection functioning as a lever arm or keel. In someembodiments, even a slightly angled projection (e.g., about 5 to about10 degrees) can serve to reduce the tendency of the device to rotate ormigrate if it has sufficient surface area and length (about 3 mm toabout 30 mm). As shown previously in FIGS. 25 and 34, one embodiment ofan anulus augmentation device can have one or more corners, sides orprojections connected at the opposing end of the devices midsection ormiddle portion. Such a configuration is especially effective whenimplanted into an intervertebral disc such that the midsection of thebarrier is inserted along the posterior anulus and the corners and sideprojections are inserted along the posterio-lateral corners and lateralanulus respectively. In one embodiment, the corner sections extend awayfrom the posterior anulus toward the anterior of the disc. Theprojections that project away from the posterior anulus at an angle(about 90 degrees or through a radius of curvature resulting in an anglefrom about 30 to about 150 degrees) are substantially parallel with oradjacent to the lateral anulus. Thus, the projection portion of theimplant in its implanted orientation is at once off-angle to theposterior anulus or midsection of the barrier and parallel to thelateral anulus. Because the anulus defines a bounded area such aprojection may indeed collide with or be parallel with another adjacentor opposing surface of the anulus but still function to stabilize thedevice along the other surface. The device can also be designed with oneor more projections that are angled toward the medial, anterior,posterior, or lateral portion of the disc such that the projectioncontacts mostly or exclusively nucleus tissue or endplate. For example,a looped projection connected at the top and bottom and/or opposing endsof the support member, frame, or patch can be configured to extendacross the disc from about 3 mm to about 30 mm and only contact nucleustissue. In another embodiment, one or more projections can be orientedinto a defect in the anulus and occupy less than or all of its volume.In another embodiment, a projection situated within a defect may beanchored into an endplate adjacent the defect. FIGS. 75A-L show animplant 610 (e.g., an annulus augmentation device such as a mesh) havingone or more projections extending into the disc or into a defect.

A stabilizing projection according to one or more embodiments of theinvention can be integral or affixed to the surgical mesh, patch, plate,biocompatible support member or barrier device. The stabilizingprojection can also be independent of or coupled to at least a portionof the frame or the membrane. The stabilizing projection can beconstructed from the same material as the frame or the membrane, or itcan be constructed from different material. The stabilizing projectioncan extend from any point or points along the device or device frameincluding its opposing ends, mid-section, along the top edge or alongthe bottom edge. The projection can also form a loop in one or moreplanes including parallel and perpendicular to the face of the device.For example, in one embodiment opposing end projections are connectedto, or are integral to, the barrier and extend out from the barrier atan angle from about 0 to about 160 degrees. In another embodiment, theprojections are joined or are simply contiguous and form a bow-shaped orcurved projection extending away from the barrier. In this embodiment,the barrier can be placed along a portion of the anulus and the bowwould extend medially into the disc. In another embodiment, the barriercan be placed along at least a portion of the posterior anulus and thebowed projection, attached at the opposing ends of the barrier frame ormembrane, would extend toward the anterior of the disc.

FIG. 76 shows an implant 610 according to one embodiment of theinvention. Here, a bow-like anterior projection 612 extends outwardlyfrom a posterior support member 614 (e.g., a patch, barrier or mesh).The projection 612 can be connected at each end of the posterior supportmember 614 along its horizontal axis. The projection 612 can be attachedat any point along the vertical axis of the end including its midline,ends, or its entirety. The projection 612 may be integral to theposterior support member 614 such that the posterior support member 614is simply formed as a band or attached separately. As shown the implant610 can be shaped like a bow. The bow can be a gentle arc, curved,re-curved one or more times, triangular, rectangular, octagonal, linkedmultiple sided, oval or circular. Though in some embodiments, an arc orsmooth bow may be advantageous for transferring loads evenly, a rigidmid-section portion or a comparatively flexible hinge-like mid-sectionalong the bow is also presented. The mid-section of the bow projectioncan have a different height than the remainder of the bow and be thesame or different (less than or greater than) height than the midsectionpatch or biocompatible support member portion of the device.

Various embodiments of the bow or arcurate member or projection 612 canact like a spring to aid in holding the ends of the patch open andagainst the anulus wall. Similarly, in one embodiment, the profile ofthe projection 612 can provide resistance to anterior travel of theimplant through the nucleus or through the opposite wall of the anulus.In another embodiment of the invention, the projection or stabilizer 612can also provide torsional resistance to the barrier 614. Finally,because the projection or bow 612 extends across the endplates itcreates an elongated profile functioning as a lever arm and thus resistsrotation along the anulus wall within the disc.

The projection, bow or band portion 612 of the implant 610 can betubular, wire-like, flat, mesh-like, curvilinear, bent, comprised of oneor more rails, or contain voids. The bow can define concavities facinginward or outward and be opposite or the same as the concavities definedby the biocompatible support member portion 614 of the implant 610. Theprojection 612 can simply be angled projections of the biocompatiblesupport member and be made of the same material and have the sameproperties. Alternatively the projection can have different propertiessuch as less flexibility or more rigidity along one or more axes.Although one projection is shown in FIG. 76, more than one bow-likeprojections may be used.

Different bow or loop projection profiles may be useful for retainingnucleus tissue within the area bounded by the implant, soft anchoring tothe nucleus or at least resisting travel through or along the nucleus,or for mechanically displacing nucleus tissue. Mechanical displacement(through pinching or pressing) of the nucleus can increase disc heightand serve to more uniformly load the anulus and improve the performanceof the implant. Also, the gap within the disc created by the bow orprojection can be left vacant or filled in with suitable nucleusaugmentation either through, or around a periphery of the implant. Thebow projection 612 can also act as a piston or shock absorber thatdeforms under compressive loading of the disc relieving some of the loadon the anulus caused by the nucleus being compressed between theendplates.

The stabilizing projection 612 can be made of the same material as thebiocompatible support member 614 (e.g., barrier, patch or mesh). In oneembodiment, the stabilizing projection 612 is an off-angle projection ofthe biocompatible support member 614 and forms a continuous loop orband. In another embodiment, the stabilizing projection 612 can be madeof a different biocompatible material, including polymers, metals,bio-materials, and grafts.

FIGS. 77A-H show various cross-sectional side views of an implant 610along a horizontal axis according to one or more embodiments of theinvention. Accordingly, a bow, band or projection can be uniform inheight or non-uniform. It can be the same height, shorter or taller thanthe patch portion of the implant. For example, in one embodiment, aprojection is narrow at the point where it connects to the posteriorsupport member component of the implant and then flairs near the midlineof the anterior bow until its height exceeds the posterior memberheight. Such a configuration might be favorable between cupped orconcave vertebral endplates when the posterior member portion of theimplant is positioned against the posterior anulus. Further, in one ormore embodiments of the invention, a projection can have differentmechanical properties than the support member or patch section of theimplant. For example, in one embodiment, a projection is more or lessflexible along one or more axes compared to the patch or biocompatiblesupport member portion of the implant. In another embodiments, aprojection can be concave along one or more axes, or can have variableregions of concavity along the same axis.

FIGS. 78A-J show various cross-sectional top views of implants 610 alonga vertical axis according to some embodiments of the invention. Forexample, FIG. 78G shows an implant (e.g., an anulus augmentation devicesuch as a mesh) that has a puckered bow-like projection that iswell-suited for disc morphology.

FIGS. 79A-F show a frontal view of a portion of various embodiments ofprojections according to one or more embodiments of the invention.

FIGS. 80A-D show various cross-sections of projection 612, according tosome embodiments of the invention.

FIGS. 81A-D show looped or bent bow-type projections 612 that arecontiguous or integral with, or are connected to the biocompatiblesupport member 614 at two or more points along a vertical or horizontalaxis. FIG. 81A shows a criss-cross loop projection. FIG. 81B shows astrap-like projection. FIG. 81C shows a projection that is integral withthe support member such that the implant forms a circular band thatserves to stabilize the device. FIG. 81D shows a box-frame typeprojection.

One skilled in the art will appreciate that any of the above proceduresinvolving nuclear augmentation and/or anulus augmentation may beperformed with or without the removal of any or all of the autologousnucleus. Further, the nuclear augmentation materials and/or the anulusaugmentation device may be designed to be safely and efficiently removedfrom the intervertebral disc in the event they are no longer required.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. An anulus augmentation device for reinforcing an intervertebral disccomprising: a support member comprising a mesh frame; wherein said meshframe comprises a “C” cross-sectional shape extending along a verticalaxis; wherein said mesh frame is elongated along a horizontal axishaving a first and second end; wherein said mesh frame comprises aplurality of flexible interconnected curvilinear members, wherein saidplurality of flexible interconnected curvilinear members are adapted toprovide flexibility and resilience to said mesh frame; a membrane,wherein said membrane covers at least a portion of said mesh frame; anda bow-like anterior stabilizing projection coupled to both ends of saidsupport member, wherein said bow-like projection extends at an anglefrom about 30-150 degrees relative to the vertical axis of the supportmember; and wherein the bow-like projection is configured to preventmigration around the circumference of an intervertebral disc.
 2. Theanulus augmentation device of claim 1, wherein said plurality offlexible interconnected curvilinear members comprise a metal alloyselected from group consisting of one or more of the following: steel,nickel titanium, and cobalt chrome.
 3. The anulus augmentation device ofclaim 1, wherein said plurality of flexible interconnected curvilinearmembers comprise a material selected from group consisting of one ormore of the following: nylon, polyvinyl alcohol, polyethylene,polyurethane, polypropylene, polycaprolactone, polyacrylate,ethylene-vinyl acetate, polystyrene, polyvinyl oxide, polyvinylfluoride, polyvinyl imidazoles, chlorosulphonated polyolefin,polyethylene oxide, polytetrafluoroethylene, acetal,poly(p-phenyleneterephtalamide) (Kevlar™), poly carbonate, carbon, andgraphite.
 4. The anulus augmentation device of claim 1, wherein saidmembrane comprises a material selected from a group consisting of one ormore of the following: polymers, elastomers, and gels.
 5. The anulusaugmentation device of claim 1, wherein said membrane comprises amaterial selected from a group consisting of one or more of thefollowing: elastin, albumin, collagen, fibrin and keratin.
 6. The anulusaugmentation device of claim 1, wherein said membrane comprises amaterial selected from a group consisting of one or more of thefollowing: antibodies, antiseptics, genetic vectors, bone morphogenicproteins, steroids, cortisones, and growth factors.
 7. The anulusaugmentation device of claim 1, wherein said membrane is a coatingmaterial.
 8. The anulus augmentation device of claim 1, where at least aportion of said plurality of flexible interconnected curvilinear membersform a horizontal member or central strut.
 9. The anulus augmentationdevice of claim 1, where said plurality of flexible interconnectedcurvilinear members are arranged in a parallel configuration.
 10. Theanulus augmentation device of claim 1, wherein said mesh frame isconcave along at least a portion of at least one axis of said meshframe.
 11. The anulus augmentation device of claim 1, wherein said meshframe has a length in the range of about 0.5 cm to about 5 cm.
 12. Theanulus augmentation device of claim 1, wherein said mesh frame is sizedto cover at least a portion of an interior surface of an anulus lamella.13. The anulus augmentation device of claim 1, wherein said mesh frameis adapted to extend circumferentially along the entire surface of ananulus lamella.
 14. The anulus augmentation device of claim 1, furthercomprising at least one projection that radiates from the mesh frame.15. The anulus augmentation device of claim 1, wherein a portion of themesh frame has a vertical cross-section of a shape selected from thegroup consisting of one or more of the following: flat, concave, convex,and curvilinear.